SEVENTH AMENDED AND RESTATED
                                   CERTIFICATE
                                       OF
                                  INCORPORATION
                                       OF
                              NxSTAGE MEDICAL, INC.
 
Jeffrey H. Burbank, being the President of NxSTAGE MEDICAL, INC., a corporation
duly organized and existing under and by virtue of the General Corporation Law
of the State of Delaware (the "Corporation"), DOES HEREBY CERTIFY as follows:
 
FIRST:      The original name of the Corporation is Qb Medical, Inc. and the
            date of filing the original Certificate of Incorporation of this
            Corporation with the Secretary of State of the State of Delaware is
            October 20, 1998; the Certificate of Incorporation of the
            Corporation was later amended on December 28, 1998, June 30, 1999,
            January 21, 2000, May 24, 2001, April 15, 2003, August 18, 2004 and
            December 28, 2004. This Seventh Amended and Restated Certificate
            amends, restates and further integrates the Corporation's
            Certificate of Incorporation pursuant to Sections 242 and 245 of the
            Delaware General Corporation Law.
 
SECOND:     The Board of Directors of the Corporation, pursuant to unanimous
            written consent, adopted resolutions authorizing the Corporation to
            integrate, restate and further amend its Certificate of
            Incorporation in its entirety to read as set forth below (the
            "Seventh Amended and Restated Certificate").
 
THIRD:      In accordance with Section 228, Section 242 and Section 245 of the
            General Corporation Law of the State of Delaware, the Seventh
            Amended and Restated Certificate was duly approved and adopted
            pursuant to a written consent signed by the holders of at least a
            majority of the issued and outstanding shares of stock entitled to
            vote thereon of the Corporation. Written notice will be given to the
            stockholders who have not consented in writing in accordance with
            Section 228(d) of the General Corporation Law of the State of
            Delaware.
 
                                  * * * * * * *
 
The Certificate of Incorporation of the Corporation is hereby amended and
restated to read in its entirety as follows:
 
                                       I.
 
      The name of the corporation is NxSTAGE MEDICAL, INC.
 
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                                       II.
 
      The address of the corporation's registered office in the State of
Delaware is 1209 Orange Street, City of Wilmington, County of New Castle, State
of Delaware, 19801. The name of the corporation's registered agent at such
address is The Corporation Trust Company.
 
                                      III.
 
      The purpose of the corporation is to engage in any lawful act or activity
for which a corporation may be organized under the General Corporation Law of
the State of Delaware.
 
                                       IV.
 
      The Corporation is authorized to issue two classes of stock to be
designated, respectively, "Common Stock" and "Preferred Stock." The Corporation
is authorized to issue Twenty Million (20,000,000) shares of Common Stock, each
having a par value of one-tenth of one cent ($0.001). The Corporation is
authorized to issue Fifteen Million Seven Hundred Fifty Nine Thousand Six
Hundred and Sixty (15,759,660) shares of Preferred Stock, each having a par
value of one-tenth of one cent ($0.001).
 
      A.    Common Stock.
 
            1. The voting, dividend and liquidation rights of the holders of the
Common Stock are subject to and qualified by the rights of the holders of the
Preferred Stock of any series as may be designated by the Board of Directors
upon any issuances of the Preferred Stock of any series.
 
            2. The holders of the Common Stock are entitled to one vote for each
share held at all meetings of shareholders. There shall be no cumulative voting.
 
            3. Dividends may be declared and paid on the Common Stock from funds
lawfully available therefor as and when determined by the Board of Directors and
subject to any preferential dividend rights of any then outstanding Preferred
Stock.
 
            4. The number of authorized shares of Common Stock may be increased
or decreased (but not below the number of shares of Common Stock then
outstanding or reserved for conversion of the outstanding Preferred Stock) by
the affirmative vote of the holders of a majority of the outstanding stock of
the Corporation entitled to vote irrespective of Section 242(b)(2) of the
General Corporation Law of the State of Delaware (voting together on an as-if
converted basis).
 
            5. Upon the dissolution or liquidation of the Corporation, whether
voluntary or involuntary, holders of Common Stock will be entitled to receive
all assets of the Corporation available for distribution, subject to any
preferential rights of any then outstanding Preferred Stock
 
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      B.    Preferred Stock
 
            1. Authorization. The Preferred Stock may be issued from time to
time in one or more series. Subject to compliance with applicable protective
rights which have been or may be granted to the Preferred Stock or a series
thereto in Certificates of Determination or the Corporation's Certificate of
Incorporation as from time to time amended, the Board of Directors is hereby
authorized with respect to any wholly unissued series of Preferred Stock and
within the limitations and restrictions set forth in this Seventh Amended and
Restated Certificate, by filing a certificate pursuant to the General
Corporation Law of the State of Delaware, to fix or alter from time to time the
designation, powers, preferences and rights of the shares of each such series
and the qualifications, limitations or restrictions thereof (including without
limitation the dividend rights, dividend rate, conversion rights, voting rights,
rights and terms of redemption (including sinking fund provisions), redemption
price or prices, and the liquidation preferences thereof), and to establish from
time to time the number of shares constituting any such series and the
designation thereof, or any of them (a "Preferred Stock Designation"); and to
increase or decrease the number of shares of any series subsequent to the
issuance of shares of that series, but not below the number of shares of such
series then outstanding. In case the number of shares of any series shall be so
decreased, the shares constituting such decrease shall resume the status that
they had prior to the adoption of the resolution originally fixing the number of
shares of such series.
 
            2. Preferred Stock Designation. One Million Eight Hundred
Seventy-Five Thousand (1,875,000) of the shares of Preferred Stock are hereby
designated "Series B Preferred Stock" (the "Series B Preferred Stock"), One
Million One Hundred Fifty Five Thousand One Hundred and Sixty Nine (1,155,169)
of the shares of Preferred Stock are hereby designated "Series C Preferred
Stock" (the "Series C Preferred Stock"), Five Million Eleven Thousand One
Hundred and Seventy Three (5,011,173) of the shares of Preferred Stock are
hereby designated "Series D Preferred Stock" (the "Series D Preferred Stock"),
Two Million Six Hundred Ninety Thousand Eight Hundred and Forty Six (2,690,846)
of the shares of Preferred Stock are hereby designated "Series E Preferred Stock
(the "Series E Preferred Stock"), Two Million Eight Hundred Twenty Nine Thousand
Six Hundred and Seventy One (2,829,671) of the shares of Preferred Stock are
hereby designated "Series F Preferred Stock (the "Series F Preferred Stock") and
Two Million One Hundred Ninety Seven Thousand Eight Hundred and One (2,197,801)
of the shares of Preferred Stock are hereby designated "Series F-1 Preferred
Stock (the "Series F-1 Preferred Stock").
 
            3. Dividends. In each fiscal year of the Corporation, the holders of
the Series B Preferred Stock, Series C Preferred Stock, Series D Preferred
Stock, Series E Preferred Stock, Series F Preferred Stock and Series F-1
Preferred Stock as may be issued and outstanding, shall be entitled to receive,
before any cash dividends shall be declared and paid upon or set aside for the
Common Stock in such fiscal year, dividends at the rate of seven percent (7.0%)
per annum of the Original Issue Price per share of the Series B Preferred Stock,
Series C Preferred Stock, Series D Preferred Stock, Series E Preferred Stock,
Series F Preferred Stock and Series F-1 Preferred Stock, respectively (as
adjusted for any stock splits, combinations, consolidations, recapitalizations,
stock dividends or the like), payable out of funds legally available therefor.
Such dividends are payable only when and if declared by the Board of Directors
and may not be
 
                                       3
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cumulative. So long as any shares of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock or Series F-1 Preferred Stock are outstanding, no dividends
(other than those payable solely in the Common Stock of the Corporation),
whether in cash or property, may be declared or paid, nor may any other
distribution be made, on any junior stock of the Corporation, nor may any junior
stock be purchased, redeemed, or otherwise acquired for value by the Corporation
(except for acquisitions of Common Stock by the Corporation pursuant to
agreements which permit the Corporation to repurchase such shares upon
termination of services by the Corporation or on exercise of the Corporation's
right of first refusal) during any fiscal year of the Corporation until the full
annual dividends on the Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and
Series F-1 Preferred Stock (and any dividends from prior year(s) declared but
unpaid) have been paid or declared and set apart. In the event dividends are
paid on any share of Common Stock, an additional dividend shall be paid with
respect to all outstanding shares of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock or Series F-1 Preferred Stock in an amount equal (on an as-if
converted basis) to the amount paid or set aside for each share of Common Stock.
The provisions of this paragraph shall not, however, apply (i) to a dividend
payable in Common Stock, (ii) upon the acquisition of shares of any junior stock
in exchange for shares of other junior stock, or (iii) to any repurchase of any
outstanding stock of the Corporation, provided that the same has been
unanimously approved by the Corporation's Board of Directors. As used herein,
the term "Original Issue Price" shall mean with respect to: (i) the Series B
Preferred Stock, $2.67 per share, (ii) the Series C Preferred Stock, $5.21 per
share, (iii) the Series D Preferred Stock, $5.97 per share, (iv) the Series E
Preferred Stock, $5.97 per share, (v) the Series F Preferred Stock, $7.28 per
share, and (vi) the Series F-1 Preferred Stock, $7.28 per share.
 
            4. Liquidation Preference.
 
                  (a) In the event of any liquidation, dissolution or winding up
of the corporation, either voluntary or involuntary, the holders of the Series B
Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E
Preferred Stock, Series F Preferred Stock and Series F-1 Preferred Stock shall
be entitled to receive, prior and in preference to any distribution of any of
the assets or surplus funds of the Corporation to the holders of the Common
Stock by reason of their ownership thereof, an amount equal to the Original
Issue Price per share of the Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock or
Series F-1 Preferred Stock (as adjusted for any combinations, consolidations, or
stock dividends of the Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock or
Series F-1 Preferred Stock with respect to such shares of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock or Series F-1 Preferred Stock, as the case may
be), plus all declared but unpaid dividends on such share for each share of
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock and Series F-1 Preferred
Stock then held by them and no more (such amount in each case, a "Liquidation
Amount"). If upon the occurrence of such event, the assets and funds thus
distributed among the holders of the Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
 
                                       4
<PAGE>
 
Preferred Stock and Series F-1 Preferred Stock shall be insufficient to permit
the payment to such holders of the full Liquidation Amount, then the entire
assets and funds of the Corporation legally available for distribution shall be
distributed ratably among the holders of the Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock in proportion to the Liquidation
Amount of the respective series, and ratably among the holders of each series in
proportion to the amount of stock of such series held by each such holder.
 
                  (b) After payment to the holders of the Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock and Series F-1 Preferred Stock of the
Liquidation Amount, the entire remaining assets and funds of the Corporation
legally available for distribution, if any, shall be distributed ratably among
the holders of the Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock , Series F-1
Preferred Stock and Common Stock in proportion to the number of shares of Series
B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E
Preferred Stock, Series F Preferred Stock, Series F-1 Preferred Stock and Common
Stock then held by them with each share of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock being treated as the shares of
Common Stock into which such Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock or
Series F-1 Preferred Stock could then be converted (and taking into
consideration any adjustment to the Series F-1 Conversion Price pursuant to
Section 10(c)(ii) hereof).
 
                  (c) A sale of all or substantially all of the assets of the
Corporation to a person or entity other than a wholly-owned subsidiary or
affiliate of the Corporation (an "Asset Transfer") or a consolidation or merger
of the Corporation with or into any other corporation or corporations in which
more than fifty percent (50%) of the voting power of the surviving entity,
calculated on an as-if-converted basis, is not owned by persons who were holders
of capital stock or securities convertible into capital stock of the Corporation
immediately prior to such merger, consolidation or sale (an "Acquisition") will
be deemed a liquidation, dissolution or winding up within the meaning of this
Section 4. All consideration payable to the stockholders of the Corporation in
connection with any such Acquisition, or all consideration payable to the
Corporation and distributable to its stockholders, together with all other
available assets of the Corporation (net of obligations owed by the Corporation
that are senior to the Corporation's Preferred Stock), in connection with any
such Asset transfer, shall be, as applicable, paid by the purchaser to the
holders of, or distributed by the Corporation in redemption (out of funds
legally available therefor) of, the Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock and Series F-1 Preferred Stock and Common Stock, in accordance with the
preferences and priorities set forth in Subsections 4(a) and 4(b) above, with
such preferences and priorities specifically intended to be applicable in any
such Acquisition or Asset Transfer as if such transaction were a liquidation,
dissolution or winding up of the Corporation. In furtherance of the foregoing,
the Corporation shall take such actions as are necessary to give effect to the
provisions of this Subsection 4(c), including without limitation, (i) in the
case of an Acquisition, causing the definitive agreement relating to such
Acquisition to provide for a rate at which the shares of Series B Preferred
Stock, Series C
 
                                       5
<PAGE>
 
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock are converted into or exchanged
for cash, new securities or other property which gives effect to the preferences
and priorities set forth in Subsections 4(a) and 4(b) above, or (ii) in the case
of an Asset Transfer, redeeming the Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock and Series F-1 Preferred Stock. The Corporation shall promptly provide to
the holders of shares of Preferred Stock such information concerning the terms
of such Acquisition or Asset Transfer, and the value of the assets of the
Corporation as may reasonably be requested by such holders. The amount deemed
distributed to the holders of Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock and Series F-1 Preferred Stock upon any such transaction shall be the cash
or the value of the property, rights or securities distributed to such holders
by the Corporation or the acquiring person, firm or other entity, as applicable.
 
            5. Voting Rights.
 
                  (a) Series B Preferred Stock Voting Rights. Except as
otherwise expressly provided herein or as required by law, the holder of each
share of the Series B Preferred Stock is entitled to one vote per share of the
Common Stock into which such share of Series B Preferred Stock could be
converted, has voting rights and powers equal to the voting rights and powers of
the Common Stock (except as otherwise expressly provided herein or as required
by law, voting together with the Common Stock, the Series C Preferred Stock, the
Series D Preferred Stock, the Series E Preferred Stock, the Series F Preferred
Stock and the Series F-1 Preferred Stock as a single class) and is entitled to
notice of any shareholders' meeting in accordance with the Bylaws of the
Corporation.
 
                  (b) Series C Preferred Stock Voting Rights. Except as
otherwise expressly provided herein or as required by law, the holder of each
share of the Series C Preferred Stock is entitled to one vote per share of the
Common Stock into which such share of Series C Preferred Stock could be
converted, has voting rights and powers equal to the voting rights and powers of
the Common Stock (except as otherwise expressly provided herein or as required
by law, voting together with the Common Stock, the Series B Preferred Stock, the
Series D Preferred Stock, the Series E Preferred Stock, the Series F Preferred
Stock and the Series F-1 Preferred Stock as a single class) and is entitled to
notice of any shareholders' meeting in accordance with the Bylaws of the
Corporation.
 
                  (c) Series D Preferred Stock Voting Rights. Except as
otherwise expressly provided herein or as required by law, the holder of each
share of the Series D Preferred Stock is entitled to one vote per share of the
Common Stock into which such share of Series D Preferred Stock could be
converted, has voting rights and powers equal to the voting rights and powers of
the Common Stock (except as otherwise expressly provided herein or as required
by law, voting together with the Common Stock, the Series B Preferred Stock, the
Series C Preferred Stock, the Series E Preferred Stock, the Series F Preferred
Stock and the Series F-1 Preferred Stock as a single class) and is entitled to
notice of any shareholders' meeting in accordance with the Bylaws of the
Corporation.
 
                                       6
<PAGE>
 
                  (d) Series E Preferred Stock Voting Rights. Except as
otherwise expressly provided herein or as required by law, the holder of each
share of the Series E Preferred Stock is entitled to one vote per share of the
Common Stock into which such share of Series E Preferred Stock could be
converted, has voting rights and powers equal to the voting rights and powers of
the Common Stock (except as otherwise expressly provided herein or as required
by law, voting together with the Common Stock, the Series B Preferred Stock, the
Series C Preferred Stock, the Series D Preferred Stock, the Series F Preferred
Stock and the Series F-1 Preferred Stock as a single class) and is entitled to
notice of any shareholders' meeting in accordance with the Bylaws of the
Corporation.
 
                  (e) Series F Preferred Stock Voting Rights. Except as
otherwise expressly provided herein or as required by law, the holder of each
share of the Series F Preferred Stock is entitled to one vote per share of the
Common Stock into which such share of Series F Preferred Stock could be
converted, has voting rights and powers equal to the voting rights and powers of
the Common Stock (except as otherwise expressly provided herein or as required
by law, voting together with the Common Stock, the Series B Preferred Stock, the
Series C Preferred Stock, the Series D Preferred Stock, the Series E Preferred
Stock and the Series F-1 Preferred Stock as a single class) and is entitled to
notice of any shareholders' meeting in accordance with the Bylaws of the
Corporation.
 
                  (f) Series F-1 Preferred Stock Voting Rights. Except as
otherwise expressly provided herein or as required by law, the holder of each
share of the Series F-1 Preferred Stock is entitled to one vote per share of the
Common Stock into which such share of Series F-1 Preferred Stock could be
converted, has voting rights and powers equal to the voting rights and powers of
the Common Stock (except as otherwise expressly provided herein or as required
by law, voting together with the Common Stock, the Series B Preferred Stock, the
Series C Preferred Stock, the Series D Preferred Stock, Series E Preferred Stock
and the Series F Preferred Stock as a single class) and is entitled to notice of
any shareholders' meeting in accordance with the Bylaws of the Corporation.
 
                  (g) Separate Vote of Preferred Stock. For so long as at least
One Hundred Thousand (100,000) shares of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and/or Series F-1 Preferred Stock remain outstanding, in
addition to any other vote or consent required herein or by law, the vote or
written consent of the holders of at least 66 2/3% of the outstanding shares of
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock and Series F-1 Preferred
Stock voting together as a single class on an as-if-converted basis, shall be
required to effect or validate any action which:
 
                        (i) adversely alters or changes the voting powers,
                        preferences, or other rights or privileges,
                        qualifications, limitations or restrictions of the
                        Series B Preferred Stock, Series C Preferred Stock,
                        Series D Preferred Stock, Series E Preferred Stock,
                        Series F Preferred Stock or Series F-1 Preferred Stock
                        whether by merger, consolidation or otherwise;
 
                                       7
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                        (ii) authorizes any class or series, or increases,
                        whether by reclassification or otherwise, the authorized
                        amount of any class or series, of equity securities of
                        the Corporation senior to or on a parity with the Series
                        B Preferred Stock, Series C Preferred Stock, Series D
                        Preferred Stock, Series E Preferred Stock, Series F
                        Preferred Stock and Series F-1 Preferred Stock in right
                        of liquidation preference or dividends;
 
                        (iii) increases or decreases (other than by redemption
                        or conversion) the authorized number of shares of the
                        Series B Preferred Stock, Series C Preferred Stock,
                        Series D Preferred Stock, Series E Preferred Stock,
                        Series F Preferred Stock or Series F-1 Preferred Stock;
 
                        (iv) increases or decreases the authorized number of
                        Directors of the Corporation from seven (7);
 
                        (v) results in the redemption, repurchase, payment of
                        dividends or other distributions with respect to junior
                        stock (except for acquisitions of Common Stock of the
                        Corporation pursuant to agreements which permit the
                        Corporation to repurchase such shares upon termination
                        of services to the Corporation or in exercise of the
                        Corporation's first right of refusal upon a proposed
                        transfer);
 
                        (vi) authorizes an Acquisition or Asset Transfer;
 
                        (vii) results in the taxation of the holders of the
                        shares of Series B Preferred Stock, Series C Preferred
                        Stock, Series D Preferred Stock, Series E Preferred
                        Stock, Series F Preferred Stock or Series F-1 Preferred
                        Stock under Section 305 of the Internal Revenue Code, as
                        from time to time amended; or
 
                        (viii) amends, alters, repeals or waives any provisions
                        of the Seventh Amended and Restated Certificate or the
                        Bylaws of the Corporation with respect to the Series B
                        Preferred Stock, Series C Preferred Stock, Series D
                        Preferred Stock, Series E Preferred Stock, Series F
                        Preferred Stock or Series F-1 Preferred Stock whether by
                        merger, consolidation or otherwise.
 
; provided that any action falling within the provisions of (i) or (viii) above
which (a) adversely applies to the holders of the Series D or Series E Preferred
Stock in a different manner from the holders of any other series of Preferred
Stock (it being expressly understood that an offering of equity securities of
the Corporation at a price below the original issue price of the Series D or
Series E Preferred Stock does not constitute an action which adversely applies
to the holders of the Series D or Series E Preferred Stock for purposes hereof),
or (b) which amends the definition
 
                                       8
<PAGE>
 
of Qualified Public Offering in Section 10(m) of this Seventh Amended and
Restated Certificate to an amount lower than that contemplated in this Seventh
Amended and Restated Certificate, shall also require the approval of at least
eighty-five percent (85%) of the Series D or Series E Preferred Stock, as the
case may be, with each Series voting as a single series.
 
            6. Consent for Certain Repurchases Deemed to be Distributions. Each
holder of an outstanding share of Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock or Series F-1 Preferred Stock is deemed to have consented, for purposes of
the General Corporation Law of Delaware, to distributions made by the
Corporation in connection with the repurchase at cost (or such other price as
may be agreed to by the Corporation's Board of Directors) of shares of capital
stock issued to or held by officers, directors, employees, or consultants upon
termination of their employment or services pursuant to agreements providing for
the right of said repurchase between the Corporation and such persons.
 
            7. Residual Rights. All rights accruing to the outstanding shares of
the Corporation not expressly provided for to the contrary herein are vested in
the Common Stock.
 
            8. No Reissuance of Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock or Series F-1 Preferred Stock. No share or shares of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock or Series F-1 Preferred Stock acquired by the
Corporation by reason of redemption, purchase, conversion or otherwise will be
reissued, and all such shares shall be returned to the status of undesignated
shares of Preferred Stock.
 
            9. Redemption Rights. The Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock are not subject to redemption, as
a whole or in part; but on or after May 1, 2007, upon written request of seventy
percent (70%) of the holders of the outstanding shares of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock or Series F-1 Preferred Stock, voting on an
as-if-converted basis, together as a single class and not as separate series,
the Corporation will redeem all of the Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock at the Original Issue Price of
such shares of Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock or Series
F-1 Preferred Stock, as the case may be (as adjusted for any combinations,
consolidations or stock dividends of the Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock or Series F-1 Preferred Stock with respect to such shares of
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock or Series F-1 Preferred
Stock, as the case may be), plus all declared but unpaid dividends on such share
for each share of Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock or Series
F-1 Preferred Stock (such amount in each case a "Redemption Price"), to the
extent funds are legally available therefor. If the funds of the Corporation
legally available are insufficient to repurchase all of the
 
                                       9
<PAGE>
 
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock and Series F-1 Preferred
Stock, then those funds which are legally available shall be used to redeem the
maximum number of shares of Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and
Series F-1 Preferred Stock ratably among the holders of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock and Series F-1 Preferred Stock in proportion to
the Redemption Price of the respective series, and ratably among the holders of
each series in proportion to the amount of stock of such series held by each
such holder. Notwithstanding anything herein to the contrary, those shares of
Preferred Stock not so redeemed shall remain outstanding and shall be entitled
to all of the rights, preferences and privileges provided herein. From time to
time thereafter when additional funds of the Corporation are legally available
for redemption of shares of Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and
Series F-1 Preferred Stock, such funds shall promptly be used to redeem the
balance of the shares which the Corporation was obliged to redeem on the
redemption date but has not yet redeemed.
 
            10. Conversion Rights. The holders of the Series B Preferred Stock,
Series C Preferred Stock, Series D Preferred Stock, Series E Preferred Stock,
Series F Preferred Stock and Series F-1 Preferred Stock have the following
rights with respect to the conversion of the Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock into shares of Common Stock (the
"Conversion Rights"):
 
                  (a) Optional Conversion. Subject to and in compliance with the
provisions of this Section 10, any shares of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock may, at the option of the holder,
be converted at any time into fully-paid and nonassessable shares of Common
Stock. The number of shares of Common Stock to which a holder of Series B
Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E
Preferred Stock, Series F Preferred Stock or Series F-1 Preferred Stock shall be
entitled upon conversion shall be the product obtained by multiplying the
"Series B Conversion Rate", the "Series C Conversion Rate," the "Series D
Conversion Rate", the "Series E Conversion Rate,", the "Series F Conversion
Rate" or the "Series F-1 Conversion Rate", as applicable, then in effect
(determined as provided in Section 10(b)(i), 10(b)(ii), 10(b)(iii), 10(b)(iv),
10(b)(v) or 10(b)(vi) respectively) by the number of shares of Series B
Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E
Preferred Stock, Series F Preferred Stock or Series F-1 Preferred Stock,
respectively, being converted.
 
                  (b) Conversion Rate. The conversion rate in effect at any
time:
 
                        (i) for conversion of the Series B Preferred Stock (the
                        "Series B Conversion Rate") is the quotient obtained by
                        dividing the Original Issue Price of the Series B
                        Preferred Stock by the "Series B Conversion Price,"
                        calculated as provided in Section 10(c); and
 
                                       10
<PAGE>
 
                        (ii) for conversion of the Series C Preferred Stock (the
                        "Series C Conversion Rate") is the quotient obtained by
                        dividing the Original Issue Price of the Series C
                        Preferred Stock by the "Series C Conversion Price,"
                        calculated as provided in Section 10(c).
 
                        (iii) for conversion of the Series D Preferred Stock
                        (the "Series D Conversion Rate") is the quotient
                        obtained by dividing the Original Issue Price of the
                        Series D Preferred Stock by the "Series D Conversion
                        Price," calculated as provided in Section 10(c).
 
                        (iv) for conversion of the Series E Preferred Stock (the
                        "Series E Conversion Rate") is the quotient obtained by
                        dividing the Original Issue Price of the Series E
                        Preferred Stock by the "Series E Conversion Price,"
                        calculated as provided in Section 10(c).
 
                        (v) for conversion of the Series F Preferred Stock (the
                        "Series F Conversion Rate") is the quotient obtained by
                        dividing the Original Issue Price of the Series F
                        Preferred Stock by the "Series F Conversion Price,"
                        calculated as provided in Section 10(c).
 
                        (vi) for conversion of the Series F-1 Preferred Stock
                        (the "Series F-1 Conversion Rate") is the quotient
                        obtained by dividing the Original Issue Price of the
                        Series F-1 Preferred Stock by the "Series F-1 Conversion
                        Price," calculated as provided in Section 10(c).
 
                  (c) Conversion Price.
 
                        (i) The conversion price for the Series B Preferred
                        Stock is, initially, the Original Issue Price of the
                        Series B Preferred Stock (the "Series B Conversion
                        Price"); the conversion price for the Series C Preferred
                        Stock is, initially, the Original Issue Price of the
                        Series C Preferred Stock (the "Series C Conversion
                        Price"); the conversion price for the Series D Preferred
                        Stock is, initially, the Original Issue Price of the
                        Series D Preferred Stock (the "Series D Conversion
                        Price"); the conversion price for the Series E Preferred
                        Stock is, initially, the Original Issue Price of the
                        Series E Preferred Stock (the "Series E Conversion
                        Price"); the conversion price for the Series F Preferred
                        Stock is, initially, the Original Issue Price of the
                        Series F Preferred Stock (the "Series F Conversion
                        Price") and the conversion price for the Series F-1
                        Preferred Stock is, initially, the Original Issue Price
                        of the Series F-1 Preferred Stock (the "Series F-1
                        Conversion Price" and, together with the Series B
                        Conversion Price, the Series C Conversion Price, the
                        Series D Conversion Price, Series E and the Series F
                        Conversion Price, the "Conversion Price"). The
                        Conversion Price for each series shall be
 
                                       11
<PAGE>
 
                        adjusted from time to time in accordance with this
                        Section 10. All references to the Series B Conversion
                        Price, the Series C Conversion Price, the Series D
                        Conversion Price, the Series E Conversion Price, the
                        Series F Conversion Price, the Series F-1 Conversion
                        Price or the Conversion Price herein means such
                        conversion price as so adjusted.
 
                        (ii) Notwithstanding anything to the contrary herein,
                        (x) upon the closing of an initial firmly underwritten
                        public offering of Common Stock for the account of the
                        Corporation pursuant to an effective registration
                        statement under the Securities Act of 1933 in which the
                        initial price per share to the public is less than 1.7
                        times the then effective Series F Conversion Price or
                        less than 1.5 times the then effective Series F-1
                        Conversion Price, then upon such closing, and
                        immediately prior to any conversion of the Series F or
                        Series F-1 Preferred Stock into Common Stock in
                        connection therewith, the Series F and/or Series F-1
                        Conversion Price, as applicable, shall be reduced to the
                        higher of (1) such initial price per share to the public
                        divided by 1.7 in the case of the Series F Preferred
                        Stock, and 1.5 in the case of the Series F-1 Preferred
                        Stock; and (2) $5.97 (as adjusted for stock splits,
                        stock dividends and similar events after the Original
                        Issue Date); and (y) upon the closing of an Asset
                        Transfer or Acquisition in which the total consideration
                        per share to be received by the holders of the Series F
                        or Series F-1 Preferred Stock (calculated in accordance
                        with Sections 4(a) and 4(b) and without taking into
                        account any adjustment to the Series F or Series F-1
                        Conversion Price pursuant to those Sections) is less
                        than 1.7 times the then effective Series F Conversion
                        Price or less than 1.5 times the then effective Series
                        F-1 Conversion Price, then immediately prior to the
                        closing of such Asset Transfer or Acquisition, the
                        Series F and/or Series F-1 Conversion Price, as
                        applicable, shall be reduced to the higher of (1) the
                        total consideration per share to be received by the
                        holders of Series F or Series F-1 Preferred Stock
                        (calculated in accordance with Sections 4(a) and 4(b)
                        and without taking into account any adjustment to the
                        Series F or Series F-1 Conversion Price pursuant to
                        those Sections) in the Asset Transfer or Acquisition
                        divided by 1.7 in the case of the Series F Preferred
                        Stock, and 1.5 in the case of the Series F-1 Preferred
                        Stock; and (2) $5.97 (as adjusted for stock splits,
                        stock dividends and similar events after the Original
                        Issue Date).
 
                  (d) Mechanics of Conversion. Each holder of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock or Series F-1 Preferred Stock who desires to
convert the same into shares of Common Stock pursuant to this Section 10 shall
surrender the certificate or certificates therefor,
 
                                       12
<PAGE>
 
duly endorsed, at the principal business office of the Corporation or any
transfer agent for the Preferred Stock, and shall give written notice to the
Corporation at such office that such holder elects to convert the same. Such
notice shall state the number of shares of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock or Series F-1 Preferred Stock being converted. Thereupon, the
Corporation shall promptly issue and deliver to such holder a certificate or
certificates for the number of shares of Common Stock to which such holder is
entitled and shall promptly pay in cash or, to the extent sufficient funds are
not then legally available therefor, in Common Stock (at the Common Stock's fair
market value determined by the Board of Directors as of the date of such
conversion), any declared and unpaid dividends on the shares of Series B
Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, Series E
Preferred Stock, Series F Preferred Stock or Series F-1 Preferred Stock being
converted. Such conversion shall be deemed to have been made at the close of
business on the date of such surrender of the certificates representing the
shares of Series B Preferred Stock, Series C Preferred Stock, Series D Preferred
Stock, Series E Preferred Stock, Series F Preferred Stock or Series F-1
Preferred Stock to be converted, and the person entitled to receive the shares
of Common Stock issuable upon such conversion shall be treated for all purposes
as the record holder of such shares of Common Stock on such date.
 
                  (e) Adjustment for Stock Splits and Combinations. If the
Corporation shall at any time or from time to time after the date that the first
share of Series F-1 Preferred Stock is issued (the "Original Issue Date") effect
a subdivision of the outstanding Common Stock, the Conversion Price in effect
immediately before that subdivision shall be proportionately decreased.
Conversely, if the Corporation shall at any time or from time to time after the
Original Issue Date combine the outstanding shares of Common Stock into a
smaller number of shares, the Conversion Price in effect immediately before the
combination shall be proportionately increased. Any adjustment under this
Section 10(e) shall become effective at the close of business on the date the
subdivision or combination becomes effective.
 
                  (f) Adjustment for Common Stock Dividends and Distributions.
If the Corporation at any time or from time to time after the Original Issue
Date makes, or fixes a record date for the determination of holders of Common
Stock entitled to receive, a dividend or other distribution payable in
additional shares of Common Stock, in each such event the Conversion Price that
is then in effect shall be decreased as of the time of such issuance or, in the
event such record date is fixed, as of the close of business on such record
date, by multiplying the Conversion Price then in effect by a fraction (1) the
numerator of which is the total number of shares of Common Stock issued and
outstanding immediately prior to the time of such issuance or the close of
business on such record date, and (2) the denominator of which is the total
number of shares of Common Stock issued and outstanding immediately prior to the
time of such issuance or the close of business on such record date plus the
number of shares of Common Stock issuable in payment of such dividend or
distribution; provided, however, that if such record date is fixed and such
dividend is not fully paid or if such distribution is not fully made on the date
fixed therefor, the Conversion Price shall be recomputed accordingly as of the
close of business on such record date and thereafter the Conversion Price shall
be adjusted pursuant to this Section 10 to reflect the actual payment of such
dividend or distribution.
 
                                       13
<PAGE>
 
                  (g) Adjustments for Other Dividends and Distributions. If the
Corporation at any time or from time to time after the Original Issue Date makes
a dividend or other distribution payable in securities of the Corporation other
than shares of Common Stock, provisions will be made so that the holders of the
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock and Series F-1 Preferred
Stock will receive upon conversion thereof, in addition to the number of shares
of Common Stock receivable thereupon, the amount of other securities of the
Corporation which they would have received had their Series B Preferred Stock,
Series C Preferred Stock, Series D Preferred Stock, Series E Preferred Stock,
Series F Preferred Stock and Series F-1 Preferred Stock been converted into
Common Stock on the date of such event and had they thereafter, during the
period from the date of such event to and including the conversion date,
retained such securities receivable by them as aforesaid during such period,
subject to all other adjustments called for during such period under this
Section 10 with respect to the rights of the holders of the Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock and Series F-1 Preferred Stock or with respect
to such other securities by their terms.
 
                  (h) Adjustment for Reclassification, Exchange and
Substitution. If at any time or from time to time after the Original Issue Date,
the Common Stock issuable upon the conversion of the Series B Preferred Stock,
the Series C Preferred Stock, the Series D Preferred Stock, the Series E
Preferred Stock, the Series F Preferred Stock or the Series F-1 Preferred Stock
is changed into the same or a different number of shares of any class or classes
of stock, whether by recapitalization, reclassification or otherwise (other than
an Acquisition or Asset Transfer as defined in Section 4(c) or a subdivision or
combination of shares or stock dividend or a reorganization, merger,
consolidation or sale of assets provided for elsewhere in this Section 10), in
any such event each holder of Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock or Series F-1 Preferred Stock thereafter has the right to convert such
stock into the kind and amount of stock and other securities and property
receivable upon such recapitalization, reclassification or other change by
holders of the maximum number of shares of Common Stock into which such shares
of Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock or Series F-1 Preferred
Stock, as applicable, could have been converted immediately prior to such
recapitalization, reclassification or change, all subject to further adjustment
as provided herein or with respect to such other securities or property by the
terms thereof.
 
                  (i) Reorganizations, Mergers, Consolidations or Sales of
Assets. If at any time or from time to time after the Original Issue Date, there
is a capital reorganization of the Common Stock (other than an Acquisition or
Asset Transfer as defined in Section 4(c) or a recapitalization, subdivision,
combination, reclassification, exchange or substitution of shares provided for
elsewhere in this Section 10), as a part of such capital reorganization,
provision shall be made so that the holders of the Series B Preferred Stock,
Series C Preferred Stock, Series D Preferred Stock, Series E Preferred Stock,
Series F Preferred Stock and Series F-1 Preferred Stock remaining outstanding
after the capital reorganization, will thereafter be entitled to receive, upon
conversion of the Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and Series
F-1 Preferred
 
                                       14
<PAGE>
 
Stock, the number of shares of stock or other securities or property of the
Corporation to which a holder of the number of shares of Common Stock
deliverable upon conversion would have been entitled on such capital
reorganization, subject to adjustment in respect of such stock or securities by
the terms thereof. In any such case, appropriate adjustment will be made in the
application of the provisions of this Section 10 with respect to the rights of
the holders of Series B Preferred Stock, the Series C Preferred Stock, the
Series D Preferred Stock, the Series E Preferred Stock, Series F Preferred Stock
and the Series F-1 Preferred Stock after the capital reorganization to the end
that the provisions of this Section 10 (including adjustment of the applicable
Conversion Price then in effect and the number of shares issuable upon
conversion of Series B Preferred Stock, the Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and Series
F-1 Preferred Stock) are applicable after that event and be as nearly equivalent
as practicable.
 
               (j) Sale of Shares Below Conversion Price.
 
                        (i) If at any time or from time to time after the
                        Original Issue Date, the Corporation issues or sells, or
                        is deemed by the express provisions of this subsection
                        (j) to have issued or sold, Additional Shares of Common
                        Stock (as hereinafter defined), other than as a dividend
                        or other distribution on any class of stock as provided
                        in Section 10(f) above, and other than a subdivision or
                        combination of shares of Common Stock as provided in
                        Section 10(e) above, for a price (the "Effective Price")
                        less than the then-effective Series B Conversion Price,
                        then and in each such case the then-existing Series B
                        Conversion Price shall be reduced, as of the opening of
                        business on the date of such issue or sale, to a price
                        determined by multiplying the Series B Conversion Price
                        by a fraction
 
                              (I) the numerator of which shall be
 
                                    (x) the number of shares of Common Stock
                                    deemed outstanding (as defined below)
                                    immediately prior to such issue or sale,
                                    plus
 
                                    (y) the number of shares of Common Stock
                                    which the aggregate consideration received
                                    (as defined in subsection (j)(vi)) by the
                                    Corporation for the total number of
                                    Additional Shares of Common Stock so issued
                                    would purchase at such Conversion Price, and
 
                              (II) the denominator of which shall be the number
                              of shares of Common Stock deemed outstanding (as
                              defined below) immediately prior to such issue or
                              sale plus the total number of Additional Shares of
                              Common Stock so issued.
 
                                       15
 
<PAGE>
 
                              For the purposes of the preceding sentence, the
                              number of shares of Common Stock deemed to be
                              outstanding as of a given date shall be the number
                              of shares of Common Stock actually outstanding.
 
                        (ii) If at any time or from time to time after the
                        Original Issue Date, the Corporation issues or sells, or
                        is deemed by the express provisions of this subsection
                        (j) to have issued or sold, Additional Shares of Common
                        Stock (as hereinafter defined), other than as a dividend
                        or other distribution on any class of stock as provided
                        in Section 10(f) above, and other than a subdivision or
                        combination of shares of Common Stock as provided in
                        Section 10(e) above, for the Effective Price less than
                        the then-effective Series C Conversion Price, then and
                        in each such case the then-existing Series C Conversion
                        Price shall be reduced, as of the opening of business on
                        the date of such issue or sale, to a price determined by
                        multiplying the Series C Conversion Price by a fraction
 
                              (I) the numerator of which shall be
 
                                    (x) the number of shares of Common Stock
                                    deemed outstanding (as defined below)
                                    immediately prior to such issue or sale,
                                    plus
 
                                    (y) the number of shares of Common Stock
                                    which the aggregate consideration received
                                    (as defined in subsection (j)(vi)) by the
                                    Corporation for the total number of
                                    Additional Shares of Common Stock so issued
                                    would purchase at such Conversion Price, and
 
                              (II) the denominator of which shall be the number
                              of shares of Common Stock deemed outstanding (as
                              defined below) immediately prior to such issue or
                              sale plus the total number of Additional Shares of
                              Common Stock so issued. For the purposes of the
                              preceding sentence, the number of shares of Common
                              Stock deemed to be outstanding as of a given date
                              shall be the number of shares of Common Stock
                              actually outstanding.
 
                        (iii) If at any time or from time to time after the
                        Original Issue Date, the Corporation issues or sells, or
                        is deemed by the express provisions of this subsection
                        (j) to have issued or sold, Additional Shares of Common
                        Stock (as hereinafter defined), other than as a dividend
                        or other distribution on any class of stock as provided
                        in
 
                                       16
 
<PAGE>
 
                        Section 10(f) above, and other than a subdivision or
                        combination of shares of Common Stock as provided in
                        Section 10(e) above, for the Effective Price less than
                        the then-effective Series D Conversion Price, then and
                        in each such case the then-existing Series D Conversion
                        Price shall be reduced, as of the opening of business on
                        the date of such issue or sale, to a price determined by
                        multiplying the Series D Conversion Price by a fraction
 
                              (I) the numerator of which shall be
 
                                    (x) the number of shares of Common Stock
                                    deemed outstanding (as defined below)
                                    immediately prior to such issue or sale,
                                    plus
 
                                    (y) the number of shares of Common Stock
                                    which the aggregate consideration received
                                    (as defined in subsection (j)(vi)) by the
                                    Corporation for the total number of
                                    Additional Shares of Common Stock so issued
                                    would purchase at such Conversion Price, and
 
                              (II) the denominator of which shall be the number
                              of shares of Common Stock deemed outstanding (as
                              defined below) immediately prior to such issue or
                              sale plus the total number of Additional Shares of
                              Common Stock so issued. For the purposes of the
                              preceding sentence, the number of shares of Common
                              Stock deemed to be outstanding as of a given date
                              shall be the number of shares of Common Stock
                              actually outstanding.
 
                        (iv) If at any time or from time to time after the
                        Original Issue Date, the Corporation issues or sells, or
                        is deemed by the express provisions of this subsection
                        (j) to have issued or sold, Additional Shares of Common
                        Stock (as hereinafter defined), other than as a dividend
                        or other distribution on any class of stock as provided
                        in Section 10(f) above, and other than a subdivision or
                        combination of shares of Common Stock as provided in
                        Section 10(e) above, for the Effective Price less than
                        the then-effective Series E Conversion Price, then and
                        in each such case the then-existing Series E Conversion
                        Price shall be reduced, as of the opening of business on
                        the date of such issue or sale, to a price determined by
                        multiplying the Series E Conversion Price by a fraction
 
                              (I) the numerator of which shall be
 
                                       17
 
<PAGE>
 
                                    (x) the number of shares of Common Stock
                                    deemed outstanding (as defined below)
                                    immediately prior to such issue or sale,
                                    plus
 
                                    (y) the number of shares of Common Stock
                                    which the aggregate consideration received
                                    (as defined in subsection (j)(vi)) by the
                                    Corporation for the total number of
                                    Additional Shares of Common Stock so issued
                                    would purchase at such Conversion Price, and
 
                              (II) the denominator of which shall be the number
                              of shares of Common Stock deemed outstanding (as
                              defined below) immediately prior to such issue or
                              sale plus the total number of Additional Shares of
                              Common Stock so issued. For the purposes of the
                              preceding sentence, the number of shares of Common
                              Stock deemed to be outstanding as of a given date
                              shall be the number of shares of Common Stock
                              actually outstanding.
 
                        (v) If at any time or from time to time after the
                        Original Issue Date, the Corporation issues or sells, or
                        is deemed by the express provisions of this subsection
                        (j) to have issued or sold, Additional Shares of Common
                        Stock (as hereinafter defined), other than as a dividend
                        or other distribution on any class of stock as provided
                        in Section 10(f) above, and other than a subdivision or
                        combination of shares of Common Stock as provided in
                        Section 10(e) above, for the Effective Price less than
                        the then-effective Series F Conversion Price, then and
                        in each such case the then-existing Series F Conversion
                        Price shall be reduced, as of the opening of business on
                        the date of such issue or sale, to a price determined by
                        multiplying the Series F Conversion Price by a fraction
 
                              (I) the numerator of which shall be
 
                                    (x) the number of shares of Common Stock
                                    deemed outstanding (as defined below)
                                    immediately prior to such issue or sale,
                                    plus
 
                                    (y) the number of shares of Common Stock
                                    which the aggregate consideration received
                                    (as defined in subsection (j)(vi)) by the
                                    Corporation for the total number of
                                    Additional Shares of Common Stock so
 
                                       18
 
<PAGE>
 
                                    issued would purchase at such Conversion
                                    Price, and
 
                              (II) the denominator of which shall be the number
                              of shares of Common Stock deemed outstanding (as
                              defined below) immediately prior to such issue or
                              sale plus the total number of Additional Shares of
                              Common Stock so issued. For the purposes of the
                              preceding sentence, the number of shares of Common
                              Stock deemed to be outstanding as of a given date
                              shall be the number of shares of Common Stock
                              actually outstanding.
 
                        (vi) If at any time or from time to time after the
                        Original Issue Date, the Corporation issues or sells, or
                        is deemed by the express provisions of this subsection
                        (j) to have issued or sold, Additional Shares of Common
                        Stock (as hereinafter defined), other than as a dividend
                        or other distribution on any class of stock as provided
                        in Section 10(f) above, and other than a subdivision or
                        combination of shares of Common Stock as provided in
                        Section 10(e) above, for the Effective Price less than
                        the then-effective Series F-1 Conversion Price, then and
                        in each such case the then-existing Series F-1
                        Conversion Price shall be reduced, as of the opening of
                        business on the date of such issue or sale, to a price
                        determined by multiplying the Series F-1 Conversion
                        Price by a fraction
 
                              (I) the numerator of which shall be
 
                                    (x) the number of shares of Common Stock
                                    deemed outstanding (as defined below)
                                    immediately prior to such issue or sale,
                                    plus
 
                                    (y) the number of shares of Common Stock
                                    which the aggregate consideration received
                                    (as defined in subsection (j)(vi)) by the
                                    Corporation for the total number of
                                    Additional Shares of Common Stock so issued
                                    would purchase at such Conversion Price, and
 
                              (II) the denominator of which shall be the number
                              of shares of Common Stock deemed outstanding (as
                              defined below) immediately prior to such issue or
                              sale plus the total number of Additional Shares of
                              Common Stock so issued. For the purposes of the
                              preceding sentence, the number of shares of Common
                              Stock deemed to be outstanding as of a
 
                                       19
 
<PAGE>
 
                              given date shall be the number of shares of Common
                              Stock actually outstanding.
 
                        (vii) For the purpose of making any adjustment required
                        under this Section 10(j), the consideration received by
                        the Corporation for any issue or sale of securities
 
                              (A) to the extent it consists of cash, will be
                              computed at the net amount of cash received by the
                              Corporation after deduction of any underwriting or
                              similar commissions, compensation or concessions
                              paid or allowed by the Corporation in connection
                              with such issue or sale but without deduction of
                              any expenses payable by the Corporation,
 
                              (B) to the extent it consists of property other
                              than cash, will be computed at the fair value of
                              that property as determined in good faith by the
                              Board of Directors, and
 
                              (C) if Additional Shares of Common Stock,
                              Convertible Securities (as hereinafter defined) or
                              rights or options to purchase either Additional
                              Shares of Common Stock or Convertible Securities
                              are issued or sold together with other stock or
                              securities or other assets of the Corporation for
                              a consideration which covers both, be computed as
                              the portion of the consideration so received that
                              may be reasonably determined in good faith by the
                              Board of Directors to be allocable to such
                              Additional Shares of Common Stock, Convertible
                              Securities or rights or options.
 
                        (viii) For the purpose of the adjustment required under
                        this Section 10(j), if the Corporation issues or sells
                        any rights or options for the purchase of, or stock or
                        other securities convertible into, Additional Shares of
                        Common Stock (such convertible stock or securities being
                        herein referred to as "Convertible Securities") and if
 
                              (A) the Effective Price of such Additional Shares
                              of Common Stock is less than the Series B
                              Conversion Price, then the Corporation will be
                              deemed to have issued at the time of the issuance
                              of such rights or options or Convertible
                              Securities the maximum number of Additional Shares
                              of Common Stock issuable upon exercise or
                              conversion thereof and to have received as
                              consideration for the issuance of such shares an
                              amount equal to the total amount of the
                              consideration, if any, received by the Corporation
                              for
 
                                       20
 
<PAGE>
 
                              the issuance of such rights or options or
                              Convertible Securities, plus, in the case of such
                              rights or options, the minimum amounts of
                              consideration, if any, payable to the Corporation
                              upon the exercise of such rights or options, plus,
                              in the case of Convertible Securities, the minimum
                              amounts of consideration, if any, payable to the
                              Corporation upon the conversion thereof; provided
                              that if in the case of Convertible Securities the
                              minimum amounts of such consideration cannot be
                              ascertained, but are a function of antidilution or
                              similar protective clauses, the Corporation shall
                              be deemed to have received the minimum amounts of
                              consideration without reference to such clauses;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of rights, options or
                              Convertible Securities is reduced over time or on
                              the occurrence or non-occurrence of specified
                              events other than by reason of antidilution
                              adjustments, the Effective Price shall be
                              recalculated using the figure to which such
                              minimum amount of consideration is reduced;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities is subsequently increased,
                              the Effective Price shall be again recalculated
                              using the increased minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities. No further adjustment of
                              the Series B Conversion Price, as adjusted upon
                              the issuance of such rights, options or
                              Convertible Securities, shall be made as a result
                              of the actual issuance of Additional Shares of
                              Common Stock on the exercise of any such rights or
                              options or the conversion of any such Convertible
                              Securities. If any such rights or options or the
                              conversion privilege represented by any such
                              Convertible Securities shall expire without having
                              been exercised, the Series B Conversion Price as
                              adjusted upon the issuance of such rights, options
                              or Convertible Securities shall be readjusted to
                              the Series B Conversion Price which would have
                              been in effect had an adjustment been made on the
                              basis that the only Additional Shares of Common
                              Stock so issued were the Additional Shares of
                              Common Stock, if any, actually issued or sold on
                              the exercise of such rights or options or rights
                              of conversion of such Convertible Securities, and
                              such Additional Shares of Common Stock, if any,
                              were issued or sold for the consideration actually
                              received by the Corporation upon such exercise,
                              plus the consideration, if
 
                                       21
 
<PAGE>
 
                              any, actually received by the Corporation for the
                              granting of all such rights or options, whether or
                              not exercised, plus the consideration received for
                              issuing or selling the Convertible Securities
                              actually converted, plus the consideration, if
                              any, actually received by the Corporation on the
                              conversion of such Convertible Securities,
                              provided that such readjustment shall not apply to
                              prior conversions of Series B Preferred Stock; and
 
                              (B) if the Effective Price of such Additional
                              Shares of Common Stock is less than the Series C
                              Conversion Price, then the Corporation will be
                              deemed to have issued at the time of the issuance
                              of such rights or options or Convertible
                              Securities the maximum number of Additional Shares
                              of Common Stock issuable upon exercise or
                              conversion thereof and to have received as
                              consideration for the issuance of such shares an
                              amount equal to the total amount of the
                              consideration, if any, received by the Corporation
                              for the issuance of such rights or options or
                              Convertible Securities, plus, in the case of such
                              rights or options, the minimum amounts of
                              consideration, if any, payable to the Corporation
                              upon the exercise of such rights or options, plus,
                              in the case of Convertible Securities, the minimum
                              amounts of consideration, if any, payable to the
                              Corporation upon the conversion thereof; provided
                              that if in the case of Convertible Securities the
                              minimum amounts of such consideration cannot be
                              ascertained, but are a function of antidilution or
                              similar protective clauses, the Corporation shall
                              be deemed to have received the minimum amounts of
                              consideration without reference to such clauses;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of rights, options or
                              Convertible Securities is reduced over time or on
                              the occurrence or non-occurrence of specified
                              events other than by reason of antidilution
                              adjustments, the Effective Price shall be
                              recalculated using the figure to which such
                              minimum amount of consideration is reduced;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities is subsequently increased,
                              the Effective Price shall be again recalculated
                              using the increased minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities. No further adjustment of
                              the Series C Conversion Price, as adjusted upon
                              the issuance of such rights, options or
                              Convertible Securities, shall be made as a result
                              of the actual issuance of Additional Shares of
                              Common Stock on the exercise of any such rights or
                              options or the conversion of any such Convertible
                              Securities. If any such rights or options or the
                              conversion privilege represented by any such
                              Convertible Securities shall expire without having
                              been exercised, the Series C Conversion Price as
                              adjusted upon the issuance of such
 
                                       22
 
<PAGE>
 
 
                              rights, options or Convertible Securities shall be
                              readjusted to the Series C Conversion Price which
                              would have been in effect had an adjustment been
                              made on the basis that the only Additional Shares
                              of Common Stock so issued were the Additional
                              Shares of Common Stock, if any, actually issued or
                              sold on the exercise of such rights or options or
                              rights of conversion of such Convertible
                              Securities, and such Additional Shares of Common
                              Stock, if any, were issued or sold for the
                              consideration actually received by the Corporation
                              upon such exercise, plus the consideration, if
                              any, actually received by the Corporation for the
                              granting of all such rights or options, whether or
                              not exercised, plus the consideration received for
                              issuing or selling the Convertible Securities
                              actually converted, plus the consideration, if
                              any, actually received by the Corporation on the
                              conversion of such Convertible Securities,
                              provided that such readjustment shall not apply to
                              prior conversions of Series C Preferred Stock.
 
                              (C) if the Effective Price of such Additional
                              Shares of Common Stock is less than the Series D
                              Conversion Price, then the Corporation will be
                              deemed to have issued at the time of the issuance
                              of such rights or options or Convertible
                              Securities the maximum number of Additional Shares
                              of Common Stock issuable upon exercise or
                              conversion thereof and to have received as
                              consideration for the issuance of such shares an
                              amount equal to the total amount of the
                              consideration, if any, received by the Corporation
                              for the issuance of such rights or options or
                              Convertible Securities, plus, in the case of such
                              rights or options, the minimum amounts of
                              consideration, if any, payable to the Corporation
                              upon the exercise of such rights or options, plus,
                              in the case of Convertible Securities, the minimum
                              amounts of consideration, if any, payable to the
                              Corporation upon the conversion thereof; provided
                              that if in the case of Convertible Securities the
                              minimum amounts of such consideration cannot be
                              ascertained, but are a function of antidilution or
                              similar protective clauses, the Corporation
 
                                       23
 
<PAGE>
 
                              shall be deemed to have received the minimum
                              amounts of consideration without reference to such
                              clauses; provided further that if the minimum
                              amount of consideration payable to the Corporation
                              upon the exercise or conversion of rights, options
                              or Convertible Securities is reduced over time or
                              on the occurrence or non-occurrence of specified
                              events other than by reason of antidilution
                              adjustments, the Effective Price shall be
                              recalculated using the figure to which such
                              minimum amount of consideration is reduced;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities is subsequently increased,
                              the Effective Price shall be again recalculated
                              using the increased minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities. No further adjustment of
                              the Series D Conversion Price, as adjusted upon
                              the issuance of such rights, options or
                              Convertible Securities, shall be made as a result
                              of the actual issuance of Additional Shares of
                              Common Stock on the exercise of any such rights or
                              options or the conversion of any such Convertible
                              Securities. If any such rights or options or the
                              conversion privilege represented by any such
                              Convertible Securities shall expire without having
                              been exercised, the Series D Conversion Price as
                              adjusted upon the issuance of such rights, options
                              or Convertible Securities shall be readjusted to
                              the Series D Conversion Price which would have
                              been in effect had an adjustment been made on the
                              basis that the only Additional Shares of Common
                              Stock so issued were the Additional Shares of
                              Common Stock, if any, actually issued or sold on
                              the exercise of such rights or options or rights
                              of conversion of such Convertible Securities, and
                              such Additional Shares of Common Stock, if any,
                              were issued or sold for the consideration actually
                              received by the Corporation upon such exercise,
                              plus the consideration, if any, actually received
                              by the Corporation for the granting of all such
                              rights or options, whether or not exercised, plus
                              the consideration received for issuing or selling
                              the Convertible Securities actually converted,
                              plus the consideration, if any, actually received
                              by the Corporation on the conversion of such
                              Convertible Securities, provided that such
                              readjustment shall not apply to prior conversions
                              of Series D Preferred Stock.
 
                                       24
 
<PAGE>
 
                              (D) if the Effective Price of such Additional
                              Shares of Common Stock is less than the Series E
                              Conversion Price, then the Corporation will be
                              deemed to have issued at the time of the issuance
                              of such rights or options or Convertible
                              Securities the maximum number of Additional Shares
                              of Common Stock issuable upon exercise or
                              conversion thereof and to have received as
                              consideration for the issuance of such shares an
                              amount equal to the total amount of the
                              consideration, if any, received by the Corporation
                              for the issuance of such rights or options or
                              Convertible Securities, plus, in the case of such
                              rights or options, the minimum amounts of
                              consideration, if any, payable to the Corporation
                              upon the exercise of such rights or options, plus,
                              in the case of Convertible Securities, the minimum
                              amounts of consideration, if any, payable to the
                              Corporation upon the conversion thereof; provided
                              that if in the case of Convertible Securities the
                              minimum amounts of such consideration cannot be
                              ascertained, but are a function of antidilution or
                              similar protective clauses, the Corporation shall
                              be deemed to have received the minimum amounts of
                              consideration without reference to such clauses;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of rights, options or
                              Convertible Securities is reduced over time or on
                              the occurrence or non-occurrence of specified
                              events other than by reason of antidilution
                              adjustments, the Effective Price shall be
                              recalculated using the figure to which such
                              minimum amount of consideration is reduced;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities is subsequently increased,
                              the Effective Price shall be again recalculated
                              using the increased minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities. No further adjustment of
                              the Series E Conversion Price, as adjusted upon
                              the issuance of such rights, options or
                              Convertible Securities, shall be made as a result
                              of the actual issuance of Additional Shares of
                              Common Stock on the exercise of any such rights or
                              options or the conversion of any such Convertible
                              Securities. If any such rights or options or the
                              conversion privilege represented by any such
                              Convertible Securities shall expire without having
                              been exercised, the Series E Conversion Price as
                              adjusted upon the issuance of such rights, options
                              or Convertible Securities shall be readjusted
 
                                       25
 
<PAGE>
 
                              to the Series E Conversion Price which would have
                              been in effect had an adjustment been made on the
                              basis that the only Additional Shares of Common
                              Stock so issued were the Additional Shares of
                              Common Stock, if any, actually issued or sold on
                              the exercise of such rights or options or rights
                              of conversion of such Convertible Securities, and
                              such Additional Shares of Common Stock, if any,
                              were issued or sold for the consideration actually
                              received by the Corporation upon such exercise,
                              plus the consideration, if any, actually received
                              by the Corporation for the granting of all such
                              rights or options, whether or not exercised, plus
                              the consideration received for issuing or selling
                              the Convertible Securities actually converted,
                              plus the consideration, if any, actually received
                              by the Corporation on the conversion of such
                              Convertible Securities, provided that such
                              readjustment shall not apply to prior conversions
                              of Series E Preferred Stock.
 
                              (E) if the Effective Price of such Additional
                              Shares of Common Stock is less than the Series F
                              Conversion Price, then the Corporation will be
                              deemed to have issued at the time of the issuance
                              of such rights or options or Convertible
                              Securities the maximum number of Additional Shares
                              of Common Stock issuable upon exercise or
                              conversion thereof and to have received as
                              consideration for the issuance of such shares an
                              amount equal to the total amount of the
                              consideration, if any, received by the Corporation
                              for the issuance of such rights or options or
                              Convertible Securities, plus, in the case of such
                              rights or options, the minimum amounts of
                              consideration, if any, payable to the Corporation
                              upon the exercise of such rights or options, plus,
                              in the case of Convertible Securities, the minimum
                              amounts of consideration, if any, payable to the
                              Corporation upon the conversion thereof; provided
                              that if in the case of Convertible Securities the
                              minimum amounts of such consideration cannot be
                              ascertained, but are a function of antidilution or
                              similar protective clauses, the Corporation shall
                              be deemed to have received the minimum amounts of
                              consideration without reference to such clauses;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of rights, options or
                              Convertible Securities is reduced over time or on
                              the occurrence or non-occurrence of specified
                              events other than by reason of antidilution
                              adjustments, the Effective Price shall be
                              recalculated using the figure to which such
                              minimum amount of consideration is reduced;
 
                                       26
 
<PAGE>
 
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities is subsequently increased,
                              the Effective Price shall be again recalculated
                              using the increased minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities. No further adjustment of
                              the Series F Conversion Price, as adjusted upon
                              the issuance of such rights, options or
                              Convertible Securities, shall be made as a result
                              of the actual issuance of Additional Shares of
                              Common Stock on the exercise of any such rights or
                              options or the conversion of any such Convertible
                              Securities. If any such rights or options or the
                              conversion privilege represented by any such
                              Convertible Securities shall expire without having
                              been exercised, the Series F Conversion Price as
                              adjusted upon the issuance of such rights, options
                              or Convertible Securities shall be readjusted to
                              the Series F Conversion Price which would have
                              been in effect had an adjustment been made on the
                              basis that the only Additional Shares of Common
                              Stock so issued were the Additional Shares of
                              Common Stock, if any, actually issued or sold on
                              the exercise of such rights or options or rights
                              of conversion of such Convertible Securities, and
                              such Additional Shares of Common Stock, if any,
                              were issued or sold for the consideration actually
                              received by the Corporation upon such exercise,
                              plus the consideration, if any, actually received
                              by the Corporation for the granting of all such
                              rights or options, whether or not exercised, plus
                              the consideration received for issuing or selling
                              the Convertible Securities actually converted,
                              plus the consideration, if any, actually received
                              by the Corporation on the conversion of such
                              Convertible Securities, provided that such
                              readjustment shall not apply to prior conversions
                              of Series F Preferred Stock.
 
                              (F) if the Effective Price of such Additional
                              Shares of Common Stock is less than the Series F-1
                              Conversion Price, then the Corporation will be
                              deemed to have issued at the time of the issuance
                              of such rights or options or Convertible
                              Securities the maximum number of Additional Shares
                              of Common Stock issuable upon exercise or
                              conversion thereof and to have received as
                              consideration for the issuance of such shares an
                              amount equal to the total amount of the
                              consideration, if any, received by the Corporation
                              for the issuance of such rights or options or
 
                                       27
 
<PAGE>
 
                              Convertible Securities, plus, in the case of such
                              rights or options, the minimum amounts of
                              consideration, if any, payable to the Corporation
                              upon the exercise of such rights or options, plus,
                              in the case of Convertible Securities, the minimum
                              amounts of consideration, if any, payable to the
                              Corporation upon the conversion thereof; provided
                              that if in the case of Convertible Securities the
                              minimum amounts of such consideration cannot be
                              ascertained, but are a function of antidilution or
                              similar protective clauses, the Corporation shall
                              be deemed to have received the minimum amounts of
                              consideration without reference to such clauses;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of rights, options or
                              Convertible Securities is reduced over time or on
                              the occurrence or non-occurrence of specified
                              events other than by reason of antidilution
                              adjustments, the Effective Price shall be
                              recalculated using the figure to which such
                              minimum amount of consideration is reduced;
                              provided further that if the minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities is subsequently increased,
                              the Effective Price shall be again recalculated
                              using the increased minimum amount of
                              consideration payable to the Corporation upon the
                              exercise or conversion of such rights, options or
                              Convertible Securities. No further adjustment of
                              the Series F-1 Conversion Price, as adjusted upon
                              the issuance of such rights, options or
                              Convertible Securities, shall be made as a result
                              of the actual issuance of Additional Shares of
                              Common Stock on the exercise of any such rights or
                              options or the conversion of any such Convertible
                              Securities. If any such rights or options or the
                              conversion privilege represented by any such
                              Convertible Securities shall expire without having
                              been exercised, the Series F-1 Conversion Price as
                              adjusted upon the issuance of such rights, options
                              or Convertible Securities shall be readjusted to
                              the Series F-1 Conversion Price which would have
                              been in effect had an adjustment been made on the
                              basis that the only Additional Shares of Common
                              Stock so issued were the Additional Shares of
                              Common Stock, if any, actually issued or sold on
                              the exercise of such rights or options or rights
                              of conversion of such Convertible Securities, and
                              such Additional Shares of Common Stock, if any,
                              were issued or sold for the consideration actually
                              received by the Corporation upon such exercise,
                              plus the consideration, if any, actually received
                              by the Corporation for the granting
 
                                       28
 
<PAGE>
 
                              of all such rights or options, whether or not
                              exercised, plus the consideration received for
                              issuing or selling the Convertible Securities
                              actually converted, plus the consideration, if
                              any, actually received by the Corporation on the
                              conversion of such Convertible Securities,
                              provided that such readjustment shall not apply to
                              prior conversions of Series F-1 Preferred Stock.
 
                        (ix) "Additional Shares of Common Stock" means all
                        shares of Common Stock issued after the Original Issue
                        Date by the Corporation or deemed to be issued pursuant
                        to this Section 10(j), whether or not subsequently
                        reacquired or retired by the Corporation other than (1)
                        shares of Common Stock issued upon conversion of the
                        Series B Preferred Stock, Series C Preferred Stock,
                        Series D Preferred Stock, Series E Preferred Stock,
                        Series F Preferred Stock or Series F-1 Preferred Stock;
                        (2) shares of Common Stock and/or options, warrants or
                        other Common Stock purchase rights, and the Common Stock
                        issued pursuant to such options, warrants or other
                        rights (as adjusted for any stock dividends,
                        combinations, splits, recapitalizations and the like)
                        issued or to be issued to employees, officers or
                        directors of, or consultants or advisors to the
                        Corporation or any subsidiary pursuant to the NxSTAGE
                        MEDICAL, INC. 1999 Stock Option and Grant Plan (as the
                        same may be amended), or stock purchase or stock option
                        plans or other arrangements that are approved by the
                        Board; and (3) shares of Common Stock issued pursuant to
                        the exercise of options, warrants or convertible
                        securities outstanding as of the Original Issue Date.
 
                        (x) Notwithstanding the foregoing, no adjustment shall
                        be made to the Series B, Series C, Series D, Series E,
                        Series F or Series F-1 Conversion Price of any shares of
                        Series B, Series C, Series D, Series E, Series F or
                        Series F-1 Preferred Stock (the "Existing Preferred
                        Stock") pursuant to the provisions of Section 10(j) if
                        the holder of such Preferred Stock does not purchase,
                        its Pro Rata Share (as defined below) of the Available
                        Shares (as defined below) issued at an Effective Price
                        for the Additional Shares of Common Stock less than the
                        then-existing Series B, Series C, Series D, Series E,
                        Series F or Series F-1 Conversion Price, as the case may
                        be, and, in such event, all shares of Existing Preferred
                        Stock held by such holder whose then effective
                        Conversion Price is greater than the Effective Price of
                        the Additional Shares of Common Stock , as the case may
                        be, shall be mandatorily converted into shares of New
                        Preferred Stock (as defined below) pursuant to the
                        provisions set forth below. For purposes hereof, each
                        Preferred Stockholder's "Pro Rata Share"
 
                                       29
 
<PAGE>
 
                        shall mean the quotient of the holder's total number of
                        issued and outstanding shares in the Corporation
                        (Preferred and Common) on a fully converted basis
                        divided by the total number of issued and outstanding
                        shares in the Corporation (Preferred and Common) on a
                        fully converted basis. "Available Shares" means the
                        Additional Shares of Common Stock or Convertible
                        Securities to be offered less (i) the Additional Shares
                        of Common Stock or Convertible Securities to be
                        purchased by a new investor (defined as any investor
                        that is unaffiliated with the holders of the
                        Corporation's Preferred Stock immediately prior to the
                        offer (the "Existing Preferred Stockholders")) and (ii)
                        any additional amount to be purchased by an Existing
                        Preferred Stockholder in excess of its Pro Rata Share.
                        For purposes of determining the number of shares of
                        Series B, Series C, Series D, Series E, Series F and
                        Series F-1 Preferred Stock, respectively, owned by a
                        holder, and for determining the number of Available
                        Shares a holder has purchased, all shares held by
                        affiliates of such holder shall be aggregated with such
                        holder's shares and all shares purchased by affiliates
                        of such holder shall be aggregated with the shares
                        purchased by such holder (provided that no shares or
                        securities shall be attributed to more than one entity
                        or person within any such group of affiliated entities
                        or persons). The mandatory conversion pursuant to this
                        clause (ix) shall be effected as follows:
 
                              (1) In the event that any holder of Existing
                              Preferred Stock does not purchase its Pro Rata
                              Share of the Available Shares, then effective
                              upon, subject to, and concurrently with, the
                              consummation of the sale of Additional Shares of
                              Common Stock referred to above (the "Financing"),
                              all shares of Series B, Series C, Series D, Series
                              E, Series F and Series F-1 Preferred Stock held by
                              such holder whose then effective Conversion Price
                              is greater than the Effective Price of the
                              Additional Shares of Common Stock, as the case may
                              be, shall automatically, and without any further
                              action on the part of such holder, be converted on
                              a share-for-share basis into shares of newly
                              created series of Preferred Stock (having such
                              number of shares as the Board of Directors may by
                              resolution fix, and to be designated Series B-I,
                              Series C-I, Series D-I, Series E-I, Series F-I and
                              Series F-1-I, respectively, as the case may be),
                              which newly created series shall be identical in
                              all respects to the Series B, Series C, Series D,
                              Series E, Series F and Series F-1 Preferred Stock,
                              respectively, except that (i) the conversion price
                              of such series shall be fixed at the Series B,
                              Series C, Series D, Series E, Series F and Series
                              F-1 Conversion Price, respectively, in effect
                              immediately prior to the consummation of the
                              Financing and shall not be
 
                                       30
 
<PAGE>
 
                              subject to any further adjustment under Section
                              10(j), (ii) such new series shall not include a
                              provision analogous to this Section 10(j)(x) and
                              (iii) the terms of such new series may vary from
                              the terms of the Series B, Series C, Series D,
                              Series E, Series F and Series F-1 Preferred Stock,
                              respectively, to the extent deemed necessary by
                              the Board of Directors to accomplish the intent of
                              this Section (such new series of Preferred Stock,
                              the "New Preferred Stock"). The Board of Directors
                              shall take all necessary actions to designate any
                              such series of New Preferred Stock. Upon such
                              conversion (a "Special Mandatory Conversion"), any
                              shares of Series B, Series C, Series D, Series E,
                              Series F and Series F-1 Preferred Stock,
                              respectively, so converted shall be cancelled and
                              not subject to reissuance.
 
                              (2) Upon a Special Mandatory Conversion, each
                              holder of shares of Existing Preferred Stock
                              converted pursuant to Section 10(j)(x) shall
                              surrender his, her or its certificate or
                              certificates for all such shares to the
                              Corporation at the place designated in such
                              notice, and shall thereafter receive certificates
                              for the number of shares of New Preferred Stock to
                              which such holder is entitled pursuant to this
                              Section 10(j)(x). All rights with respect to the
                              Existing Preferred Stock converted pursuant to
                              Section 10(j)(x) will terminate, except only the
                              rights of the holders thereof, upon surrender of
                              their certificate or certificates therefor, to
                              receive certificates for the number of shares of
                              New Preferred Stock into which such Existing
                              Preferred Stock has been converted, and payment of
                              any declared but unpaid dividends thereon. If so
                              required by the Corporation, certificates
                              surrendered for conversion shall be endorsed or
                              accompanied by written instrument or instruments
                              of transfer, in form satisfactory to the
                              Corporation, duly executed by the registered
                              holder or by his, her or its attorney duly
                              authorized in writing. As soon as practicable
                              after the Special Mandatory Conversion and the
                              surrender of the certificate or certificates for
                              Existing Preferred Stock so converted, the
                              Corporation shall cause to be issued and delivered
                              to such holder, or on his, her or its written
                              order, a certificate or certificates for the
                              number of full shares of New Preferred Stock
                              issuable on such conversion in accordance with the
                              provisions hereof.
 
                              (3) All certificates evidencing shares of Existing
                              Preferred Stock which are required to be
                              surrendered for conversion in accordance with the
                              provisions hereof shall,
 
                                       31
 
<PAGE>
 
                              from and after the time of the Special Mandatory
                              Conversion, be deemed to have been retired and
                              cancelled, and the shares of Existing Preferred
                              Stock represented thereby shall, from and after
                              the time of the Special Mandatory Conversion, be
                              deemed to have been converted into New Preferred
                              Stock for all purposes, notwithstanding the
                              failure of the holder or holders thereof to
                              surrender such certificates on or prior to such
                              date. The Corporation may thereafter take such
                              appropriate action (without the need for
                              stockholder action) as may be necessary to reduce
                              the authorized number of shares of Existing
                              Preferred Stock accordingly.
 
                              (4) Notwithstanding any other provisions in this
                              Certificate of Incorporation to the contrary, in
                              the event that one or more series of New Preferred
                              Stock are established, any reference in the terms
                              of the Series B, Series C, Series D, Series E,
                              Series F and Series F-1 Preferred Stock,
                              respectively, or in the terms of such series of
                              New Preferred Stock into which shares of such
                              series have been converted, to the rights of the
                              holders thereof to consent, vote or otherwise take
                              action separately as a class (other than a waiver
                              given with respect to the terms of Section 10(j)
                              of the Existing Preferred Stock terms, to which
                              this sentence shall not apply) shall be deemed to
                              refer to a consent, vote or other action by the
                              holders of the specified percentage of all
                              outstanding shares of such series of Existing
                              Preferred Stock and the series of New Preferred
                              Stock into which shares of such series have been
                              converted, considered together as a single class.
 
               (k) Accountants' Certificate of Adjustment. In each case of an
adjustment or readjustment of the Conversion Price for the number of shares of
Common Stock or other securities issuable upon conversion of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock and Series F-1 Preferred Stock, upon the request
of any of the holders of the Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and
Series F-1 Preferred Stock, the Corporation, at its expense, shall compute such
adjustment or readjustment in accordance with the provisions hereof and prepare
a certificate showing such adjustment or readjustment, and shall mail such
certificate, by first class mail, postage prepaid, to each registered holder of
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock,
Series E Preferred Stock, Series F Preferred Stock and Series F-1 Preferred
Stock at the holder's address as shown in the Corporation's books. The
certificate shall set forth such adjustment or readjustment, showing in detail
the facts upon which such adjustment or readjustment is based, including a
statement of (1) the consideration received or deemed to be received by the
Corporation for any Additional Shares of Common Stock issued or sold or
 
                                       32
 
<PAGE>
 
 
deemed to have been issued or sold, (2) the Conversion Price at the time in
effect, (3) the number of Additional Shares of Common Stock and (4) the type and
amount, if any, of other property which at the time would be received upon
conversion of the Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and Series
F-1 Preferred Stock.
 
               (l) Notices of Record Date. Upon (i) any taking by the
Corporation of a record of the holders of any class of securities for the
purpose of determining the holders thereof who are entitled to receive any
dividend or other distribution, or (ii) any Acquisition (as defined in Section
4(c)) or other capital reorganization of the Corporation, any reclassification
or recapitalization of the capital stock of the Corporation, any merger or
consolidation of the Corporation with or into any other Corporation, or any
Asset Transfer (as defined in Section 4(c)), or any voluntary or involuntary
dissolution, liquidation or winding up of the Corporation, the Corporation shall
mail to each holder of Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and
Series F-1 Preferred Stock at least twenty (20) days prior to the record date
specified therein a notice specifying (1) the date on which any such record is
to be taken for the purpose of such dividend or distribution and a description
of such dividend or distribution, (2) the date on which any such Acquisition,
reorganization, reclassification, transfer, consolidation, merger, Asset
Transfer, dissolution, liquidation or winding up is expected to become
effective, and the material terms of such transaction, and (3) the date, if any,
that is to be fixed as to when the holders of record of Common Stock (or other
securities) shall be entitled to exchange their shares of Common Stock (or other
securities) for securities or other property deliverable upon such Acquisition,
reorganization, reclassification, transfer, consolidation, merger, Asset
Transfer, dissolution, liquidation or winding up.
 
               (m) Automatic Conversion.
 
                        (i) Each share of Series B Preferred Stock, Series C
                        Preferred Stock, Series D Preferred Stock, Series E
                        Preferred Stock, Series F Preferred Stock and Series F-1
                        Preferred Stock shall automatically be converted into
                        shares of Common Stock, based on each then-effective
                        applicable Conversion Price, (A) at any time upon the
                        affirmative vote of the holders of at least seventy
                        percent (70%) of the outstanding shares of the Series B
                        Preferred Stock, Series C Preferred Stock, Series D
                        Preferred Stock, Series E Preferred Stock, Series F
                        Preferred Stock and Series F-1 Preferred Stock voting on
                        an as-if-converted basis, together as a single class, or
                        (B) immediately upon the closing of a firmly
                        underwritten public offering pursuant to an effective
                        registration statement under the Securities Act of 1933,
                        as amended, covering the offer and sale of Common Stock
                        for the account of the Corporation in which the gross
                        cash proceeds to the Corporation (before underwriting
                        discounts, commissions and fees) are at least
                        $20,000,000 (a "Qualified Public Offering").
                        Notwithstanding the foregoing, Series D and Series E
                        Preferred Stock shall not be automatically
 
                                       33
 
<PAGE>
 
                        converted under (A) above unless such affirmative vote
                        includes at least 85% of the outstanding stock of Series
                        D or E, respectively. Upon such automatic conversion,
                        any declared and unpaid dividends shall be paid in
                        accordance with the provisions of Section 10(d).
 
                        (ii) Upon the occurrence of any of the events specified
                        in paragraph (i) above, the outstanding shares of Series
                        B Preferred Stock, Series C Preferred Stock, Series D
                        Preferred Stock, Series E Preferred Stock, Series F
                        Preferred Stock and Series F-1 Preferred Stock, as
                        applicable, will be converted automatically without any
                        further action by the holders of such shares and whether
                        or not the certificates representing such shares are
                        surrendered to the Corporation or its transfer agent;
                        provided, however, that the Corporation will not be
                        obligated to issue certificates evidencing the shares of
                        Common Stock issuable upon such conversion unless the
                        certificates evidencing such shares of Series B
                        Preferred Stock, Series C Preferred Stock, Series D
                        Preferred Stock, Series E Preferred Stock, Series F
                        Preferred Stock and Series F-1 Preferred Stock, as
                        applicable, are either delivered to the Corporation or
                        its transfer agent as provided below, or the holder
                        notifies the Corporation or its transfer agent that such
                        certificates have been lost, stolen or destroyed and
                        executes an agreement satisfactory to the Corporation to
                        indemnify the Corporation from any loss incurred by it
                        in connection with such certificates. Upon the
                        occurrence of such automatic conversion of any of the
                        Series B Preferred Stock, Series C Preferred Stock,
                        Series D Preferred Stock, Series E Preferred Stock,
                        Series F Preferred Stock or Series F-1 Preferred Stock,
                        the holders of Series B Preferred Stock, Series C
                        Preferred Stock, Series D Preferred Stock, Series E
                        Preferred Stock, Series F Preferred Stock or Series F-1
                        Preferred Stock shall surrender the certificates
                        representing such shares at the office of the
                        Corporation or any transfer agent for the Preferred
                        Stock. Thereupon, there shall be issued and delivered to
                        such holder promptly at such office and in its name as
                        shown on such surrendered certificate or certificates, a
                        certificate or certificates for the number of shares of
                        Common Stock into which the shares of Series B Preferred
                        Stock, Series C Preferred Stock, Series D Preferred
                        Stock, Series E Preferred Stock, Series F Preferred
                        Stock or Series F-1 Preferred Stock surrendered were
                        convertible on the date on which such automatic
                        conversion occurred, and the Corporation shall promptly
                        pay in cash or, at the option of the Corporation, Common
                        Stock (at the Common Stock's fair market value
                        determined by the Board as of the date of such
                        conversion), or, at the option of the Corporation, both,
                        all declared and unpaid dividends on the shares of
                        Series B Preferred Stock, Series C
 
                                       34
 
<PAGE>
 
                        Preferred Stock, Series D Preferred Stock, Series E
                        Preferred Stock, Series F Preferred Stock or Series F-1
                        Preferred Stock being converted, to and including the
                        date of such conversion.
 
               (n) Fractional Shares. No fractional shares of Common Stock shall
be issued upon conversion of Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock or
Series F-1 Preferred Stock. All shares of Common Stock (including fractions
thereof) issuable upon conversion of more than one share of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock, Series E Preferred
Stock, Series F Preferred Stock or Series F-1 Preferred Stock by a holder
thereof shall be aggregated for purposes of determining whether the conversion
would result in the issuance of any fractional share. If, after the
aforementioned aggregation, the conversion would result in the issuance of any
fractional share, the Corporation shall, in lieu of issuing any fractional
share, pay cash equal to the product of such fraction multiplied by the Common
Stock's fair market value (as determined by the Board) on the date of
conversion.
 
               (o) Reservation of Stock Issuable Upon Conversion. The
Corporation shall at all times reserve and keep available out of its authorized
but unissued shares of Common Stock, solely for the purpose of effecting the
conversion of the shares of the Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock and Series F-1 Preferred Stock, such number of its shares of Common Stock
as shall from time to time be sufficient to effect the conversion of all
outstanding shares of the Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and
Series F-1 Preferred Stock. If at any time the number of authorized but unissued
shares of Common Stock shall not be sufficient to effect the conversion of all
then outstanding shares of the Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Series E Preferred Stock, Series F Preferred
Stock and Series F-1 Preferred Stock, the Corporation will take such corporate
action as may, in the opinion of its counsel, be necessary to increase its
authorized but unissued shares of Common Stock to such number of shares as shall
be sufficient for such purpose.
 
               (p) Notices. Any notice required by the provisions of this
Section 10 shall be in writing and shall be deemed effectively given: (i) upon
personal delivery to the party to be notified, (ii) when sent by confirmed telex
or facsimile if sent during normal business hours of the recipient; if not, then
on the next business day, (iii) five (5) days after having been sent by
registered or certified mail, return receipt requested, postage prepaid, or (iv)
one (1) day after deposit with a nationally recognized overnight courier, having
specified next day delivery, with written verification of receipt. All notices
shall be addressed to each holder of record at the address of such holder
appearing on the books of the Corporation.
 
               (q) Payment of Taxes. The Corporation will pay all taxes (other
than taxes based upon income) and other governmental charges that may be imposed
with respect to the issue or delivery of shares of Common Stock upon conversion
of shares of Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and Series
F-1 Preferred Stock, excluding any tax or other charge imposed in connection
with any transfer involved in the issue and delivery of shares of Common Stock
in a
 
                                       35
 
<PAGE>
 
name other than that in which the shares of Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Series E Preferred Stock, Series F
Preferred Stock and Series F-1 Preferred Stock so converted were registered.
 
               (r) No Dilution or Impairment. The Corporation shall not amend
this Seventh Amended and Restated Certificate of Incorporation or participate in
any reorganization, transfer of assets, consolidation, merger, dissolution,
issue or sale of securities or any other voluntary action, for the purpose of
avoiding or seeking to avoid the observance or performance of any of the terms
to be observed or performed hereunder by the Corporation, but shall at all times
in good faith assist in carrying out all such action as may be reasonably
necessary or appropriate in order to protect the conversion rights of the
holders of the Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock and Series
F-1 Preferred Stock against dilution or other impairment.
 
                                       V.
 
      For the management of the business and for the conduct of the affairs of
the Corporation, and in further definition, limitation and regulation of the
powers of the Corporation, of its directors and of its stockholders or any class
thereof, as the case may be, it is further provided that:
 
      A. The management of the business and the conduct of the affairs of the
Corporation shall be vested in its Board of Directors. Subject to the
restrictions contained in this Seventh Amended and Restated Certificate, the
number of directors which shall constitute the whole Board of Directors shall be
fixed by the Board of Directors in the manner provided in the Bylaws.
 
      B. Subject to the restrictions set forth in this Seventh Amended and
Restated Certificate, the Board of Directors may from time to time make, amend,
supplement or repeal the Bylaws.
 
      C. The directors of the Corporation need not be elected by written ballot
unless the Bylaws so provide.
 
                                       VI.
 
      A. A director of the Corporation shall not be personally liable to the
Corporation or its stockholders for monetary damages for any breach of fiduciary
duty as a director, except for liability (i) for any breach of the director's
duty of loyalty to the Corporation or its stockholders, (ii) for acts or
omissions not in good faith or which involve intentional misconduct or a knowing
violation of law, (iii) under Section 174 of the Delaware General Corporation
Law or (iv) for any transaction from which the director derived an improper
personal benefit. If the Delaware General Corporation Law is amended after
approval by the stockholders of this Article to authorize corporate action
further eliminating or limiting the personal liability of directors, then
 
                                       36
 
<PAGE>
 
the liability of a director shall be eliminated or limited to the fullest extent
permitted by the Delaware General Corporation Law, as so amended.
 
      B. The Corporation shall, to the fullest extent permitted by Section 145
of the General Corporation Law of Delaware, as amended from time to time,
indemnify each person who was or is a party or is threatened to be made a party
to any threatened, pending or completed action, suit or proceeding, whether
civil, criminal, administrative or investigative, by reason of the fact that he
is or was, or has agreed to become, a director or officer of the Corporation, or
is or was serving, or has agreed to serve, at the request of the Corporation, as
a director, officer or trustee of, or in a similar capacity with, another
corporation, partnership, joint venture, trust or other enterprise (including
any employee benefit plan) (all such persons being referred to hereafter as an
"Indemnitee"), or by reason of any action alleged to have been taken or omitted
in such capacity, against all expenses (including attorneys' fees), judgments,
fines and amounts paid in settlement actually and reasonably incurred by or on
behalf of an Indemnitee in connection with such action, suit or proceeding and
any appeal therefrom.
 
      As a condition precedent to his right to be indemnified, the Indemnitee
must notify the Corporation in writing as soon as practicable of any action,
suit, proceeding or investigation involving him for which indemnity will or
could be sought; provided that any failure by an Indemnitee to promptly notify
the Corporation of any such action, suit, proceeding or investigation shall not
relieve the Corporation of its obligations under this Article VI, unless, and
only to the extent, the Corporation is materially prejudiced by such failure.
With respect to any action, suit, proceeding or investigation of which the
Corporation is so notified, the Corporation will be entitled to participate
therein at its own expense and/or to assume the defense thereof at its own
expense, with legal counsel reasonably acceptable to the Indemnitee.
 
      In the event that the Corporation does not assume the defense of any
action, suit, proceeding or investigation of which the Corporation receives
notice under this Article, the Corporation shall pay in advance of the final
disposition of such matter any expenses (including attorneys' fees) incurred by
an Indemnitee in defending a civil or criminal action, suit, proceeding or
investigation or any appeal therefrom; provided, however, that the payment of
such expenses incurred by an Indemnitee in advance of the final disposition of
such matter shall be made only upon receipt of an undertaking by or on behalf of
the Indemnitee to repay all amounts so advanced in the event that it shall
ultimately be determined that the Indemnitee is not entitled to be indemnified
by the Corporation as authorized in this Article, which undertaking shall be
accepted without reference to the financial ability of the Indemnitee to make
such repayment; and further provided that no such advancement of expenses shall
be made if it is determined that the Indemnitee did not act in good faith and in
a manner he reasonably believed to be in, or not opposed to, the best interests
of the Corporation, and, with respect to any criminal action or proceeding, had
reasonable cause to believe his conduct was unlawful.
 
      The Corporation shall not indemnify an Indemnitee seeking indemnification
in connection with a proceeding (or part thereof) initiated by such Indemnitee
unless the initiation thereof was approved by the Board of Directors of the
Corporation. In addition, the Corporation shall not indemnify an Indemnitee to
the extent such Indemnitee is reimbursed from the proceeds of insurance, and in
the event the Corporation makes any indemnification payments to an
 
                                       37
 
<PAGE>
 
Indemnitee and such Indemnitee is subsequently reimbursed from the proceeds of
insurance, such Indemnitee shall promptly refund such indemnification payments
to the Corporation to the extent of such insurance reimbursement.
 
      All determinations hereunder as to the entitlement of an Indemnitee to
indemnification or advancement of expenses shall be made in each instance by (a)
a majority vote of the directors of the Corporation consisting of persons who
are not at that time parties to the action, suit or proceeding in question
("disinterested directors"), whether or not a quorum, (b) a majority vote of a
quorum of the outstanding shares of stock of all classes entitled to vote for
directors, voting as a single class, which quorum shall consist of stockholders
who are not at that time parties to the action, suit or proceeding in question,
(c) independent legal counsel (who may, to the extent permitted by law, be
regular legal counsel to the Corporation), or (d) a court of competent
jurisdiction.
 
      The indemnification rights provided in this Article (i) shall not be
deemed exclusive of any other rights to which an Indemnitee may be entitled
under any law, agreement or vote of stockholders or disinterested directors or
otherwise, and (ii) shall inure to the benefit of the heirs, executors and
administrators of the Indemnitees. The Corporation may, to the extent authorized
from time to time by its Board of Directors, grant indemnification rights to
other employees or agents of the Corporation or other persons serving the
Corporation and such rights may be equivalent to, or greater or less than, those
set forth in this Article.
 
      C. Any repeal or modification of this Article VI shall be prospective and
shall not affect the rights under this Article VI in effect at the time of the
alleged occurrence of any act or omission to act giving rise to liability or
indemnification.
 
                                      VII.
 
      The corporation is to have perpetual existence.
 
                                      VIII.
 
      The corporation reserves the right to amend, alter, change or repeal any
provision contained in this Seventh Amended and Restated Certificate of
Incorporation, in the manner now or hereafter prescribed by statute, and all
rights conferred upon the stockholders herein are granted subject to this right.
 
                                       38
 
<PAGE>
 
      IN WITNESS WHEREOF, the Corporation has caused this Seventh Amended and
Restated Certificate of Incorporation to be signed by its President, Jeffrey H.
Burbank, this 7th day of July, 2005.
 
                                           NxSTAGE MEDICAL, INC.
 
                                           By: /s/ Jeffrey H. Burbank
                                               --------------------------------
                                               Jeffrey H. Burbank, President
<PAGE>