<PAGE>

                                                                     EXHIBIT 4.2

                                                                  EXECUTION COPY


                    AMENDED AND RESTATED INVESTORS' AGREEMENT

                                   dated as of

                                  June 19, 2000

                                      among

                 CHARLES RIVER LABORATORIES INTERNATIONAL, INC.

                                     and the

              several Stockholders from time to time parties hereto


<PAGE>

<TABLE>

<CAPTION>

<S>            <C>                                                                           <C>
                                                                                             PAGE
                                                                                             ----

                                TABLE OF CONTENTS
                                -----------------

                                    ARTICLE 1

                                   DEFINITIONS

SECTION 1.01.  DEFINITIONS......................................................................1

                                    ARTICLE 2

                              CORPORATE GOVERNANCE

SECTION 2.01.  COMPOSITION OF THE BOARD.........................................................9
SECTION 2.02.  REMOVAL..........................................................................9
SECTION 2.03.  VACANCIES........................................................................9
SECTION 2.04.  MEETINGS........................................................................10
SECTION 2.05.  ACTION BY THE BOARD.............................................................10
SECTION 2.06.  CONFLICTING CHARTER OR BYLAW PROVISIONS.........................................10

                                    ARTICLE 3

                            RESTRICTIONS ON TRANSFER

SECTION 3.01.  GENERAL.........................................................................11
SECTION 3.02.  LEGENDS.........................................................................11
SECTION 3.03.  PERMITTED TRANSFEREES...........................................................12
SECTION 3.04.  RESTRICTIONS ON TRANSFERS BY MANAGEMENT STOCKHOLDERS............................12
SECTION 3.05.  RESTRICTIONS ON TRANSFERS BY CRL................................................13
SECTION 3.06.  RESTRICTIONS ON TRANSFERS BY NEW MINORITY SHAREHOLDERS..........................14

                                    ARTICLE 4

                                DRAG-ALONG RIGHTS

SECTION 4.01.  RIGHT TO COMPEL PARTICIPATION IN CERTAIN TRANSFERS..............................14

                                    ARTICLE 5

                               REGISTRATION RIGHTS

SECTION 5.01.  DEMAND REGISTRATION.............................................................16
SECTION 5.02.  INCIDENTAL REGISTRATION.........................................................19
SECTION 5.03.  HOLDBACK AGREEMENTS.............................................................21
SECTION 5.04.  REGISTRATION PROCEDURES.........................................................21
SECTION 5.05.  INDEMNIFICATION BY THE COMPANY..................................................24
SECTION 5.06.  INDEMNIFICATION BY PARTICIPATING STOCKHOLDERS...................................25

</TABLE>


<PAGE>



<TABLE>

<CAPTION>

<S>            <C>                                                                          <C>
                                                                                             PAGE
                                                                                             ----

SECTION 5.07.  CONDUCT OF INDEMNIFICATION PROCEEDINGS..........................................25
SECTION 5.08.  CONTRIBUTION....................................................................26
SECTION 5.09.  PARTICIPATION IN PUBLIC OFFERING................................................28
SECTION 5.10.  OTHER INDEMNIFICATION...........................................................28
SECTION 5.11.  COOPERATION BY THE COMPANY......................................................28

                                    ARTICLE 6

                                  MISCELLANEOUS

SECTION 6.01.  ENTIRE AGREEMENT; EFFECTIVENESS.................................................28
SECTION 6.02.  BINDING EFFECT; BENEFIT; ACTION BY DLJMB ENTITIES; WAIVER.......................29
SECTION 6.03.  EXCLUSIVE FINANCIAL AND INVESTMENT BANKING ADVISOR..............................29
SECTION 6.04.  PRE-EMPTIVE RIGHTS..............................................................29
SECTION 6.05.  ASSIGNABILITY...................................................................30
SECTION 6.06.  AMENDMENT; WAIVER; TERMINATION..................................................30
SECTION 6.07.  NOTICES.........................................................................31
SECTION 6.08.  HEADINGS........................................................................34
SECTION 6.09.  COUNTERPARTS....................................................................34
SECTION 6.10.  APPLICABLE LAW..................................................................34
SECTION 6.11.  SPECIFIC ENFORCEMENT............................................................34
SECTION 6.12.  CONSENT TO JURISDICTION.........................................................34

</TABLE>


<PAGE>

                    AMENDED AND RESTATED INVESTORS' AGREEMENT

     AGREEMENT dated as of June 19, 2000 among Charles River Laboratories
International, Inc., a Delaware corporation (formerly Charles River Laboratories
Holdings, Inc.) (the "COMPANY"), CRL Acquisition LLC, a Delaware limited
liability company ("LLC"), the DLJMB Entities (as defined herein), DLJ
Investment Partners, L.P., DLJ Investment Funding, Inc., (collectively with DLJ
Investment Partners, L.P., "DLJIP"), The 1818 Mezzanine Fund, L.P. ("BB"),
Carlyle High Yield Partners, L.P. ("CARLYLE"), B&L CRL, Inc., a Delaware
corporation ("CRL"), Steven Chubb, William Waltrip, the TCW Entities (as defined
herein), and certain other Persons listed on the signature pages hereof (each, a
"MANAGEMENT STOCKHOLDER", and collectively, the "MANAGEMENT STOCKHOLDERS").

     WHEREAS, the parties hereto have heretofore entered into an Investors
Agreement dated as of September 29, 1999 (the "ORIGINAL AGREEMENT");

     WHEREAS, pursuant to an Agreement and Plan of Reorganization dated as of
June 6, 2000 among the Company, the LLC and CRL (the "REORGANIZATION
AGREEMENT"), the LLC has transferred to the company all of the Shares held by it
in exchange for new Shares (the "EXCHANGE") and distributed a portion of such
new Shares to the holders (the "LLC HOLDERS") of limited liability company
interests in the LLC (the "DISTRIBUTION"); and

     WHEREAS, the Company, CRL and DLJ Merchant Banking II, Inc. desire to amend
and restate the Original Agreement in its entirety, in accordance with the
procedure set forth in Section 6.07 of the Original Agreement, to reflect the
Exchange and the Distribution and to add as parties to this Agreement those LLC
Holders who were not party to the Original Agreement.

     NOW, THEREFORE, the parties hereto agree as follows:

                                    ARTICLE 1
                                   DEFINITIONS

     SECTION 1.01. DEFINITIONS. (a) The following terms, as used herein, have
the following meanings:

     "ADVERSE PERSON" means any Person whom the Board of Directors of the
Company reasonably determines is a competitor or a potential competitor of the


<PAGE>

Company or its subsidiaries in a business that is material to the Company and
its subsidiaries, taken as a whole.

     "AFFILIATE" means, with respect to any Person, any other Person directly or
indirectly controlling, controlled by, or under common control with such Person;
PROVIDED that no stockholder of the Company shall be deemed an Affiliate of any
other stockholder of the Company solely by reason of any investment in the
Company. For the purpose of this definition, the term "CONTROL" (including with
correlative meanings, the terms "CONTROLLING", "CONTROLLED BY" and "UNDER COMMON
CONTROL WITH"), when used with respect to any Person, means the possession,
directly or indirectly, of the power to direct or cause the direction of the
management and policies of such Person, whether through the ownership of voting
securities, by contract or otherwise.

     "AFFILIATED EMPLOYEE BENEFIT TRUST" means any trust that is a successor to
the assets held by a trust established under an employee benefit plan subject to
ERISA or any other trust established directly or indirectly under such plan or
any other such plan having the same sponsor.

     "BOARD" means the board of directors of the Company.

     "BUSINESS DAY" means any day except a Saturday, Sunday or other day on
which commercial banks in New York City are authorized by law to close.

     "BYLAWS" means the Bylaws of the Company, as amended from time to time.

     "CHARTER" means the Certificate of Incorporation of the Company, as amended
from time to time.

     "CLOSING DATE" means September 29, 1999.

     "COMMON STOCK" means the common stock, par value $0.01 per share, of the
Company and any stock into which such Common Stock may thereafter be converted,
exchanged or changed, and "COMMON SHARES" means shares of Common Stock.

     "COMPANY SECURITIES" means the Common Stock and securities convertible into
or exchangeable for Common Stock and options, warrants (including the Warrants)
or other rights to acquire Common Stock or any other equity security issued by
the Company; PROVIDED that notwithstanding the foregoing, the term "Company
Securities" shall not include the High Yield Warrants; and PROVIDED, FURTHER
that, for purposes of Article 3 of this Amended


                                       2
<PAGE>

and Restated Agreement, the term "Company Securities" with respect to a
Management Stockholder shall not include any Common Stock and options, warrants
or other rights to acquire Common Stock or any other equity security issued by
the Company received by such Management Stockholder on or after the date of the
Initial Public Offering, other than Common Stock issued by the Company upon
exercise of options held by such Management Stockholder under the Company's 1999
Management Incentive Plan as of the date of this Amended and Restated Agreement
(whether or not such Management Stockholder was a party hereto as of the date of
this Amended and Restated Agreement).

     "DLJMB ENTITIES" means DLJ Merchant Banking Partners II, L.P., a Delaware
limited partnership, DLJMB Funding II, Inc., a Delaware corporation, DLJ
Merchant Banking Partners II-A, L.P., a Delaware limited partnership, DLJ
Diversified Partners, L.P., a Delaware limited partnership, DLJ Diversified
Partners-A, L.P., a Delaware limited partnership, DLJ Millennium Partners, L.P.,
a Delaware limited partnership, DLJ Millennium Partners-A, L.P., a Delaware
limited partnership, DLJ First ESC, L.P., a Delaware limited partnership, DLJ
ESC II, L.P., a Delaware limited partnership ("ESC II"), DLJ Offshore Partners
II, C.V., a Netherlands Antilles limited partnership, DLJ EAB Partners, L.P., a
Delaware limited partnership, Sprout Capital VIII, L.P., a Delaware limited
partnership, Sprout Venture Capital, L.P., a Delaware limited partnership, DLJ
Capital Corp., a Delaware corporation, and the LLC, and, to the extent any of
the above shall have transferred any of their shares to "Permitted Transferees,"
such Permitted Transferees.

     "DRAG-ALONG PORTION" means, with respect to any Other Stockholder and any
class of Company Securities, the number of such class of Company Securities
beneficially owned by such Other Stockholder on a Fully Diluted basis (but
without duplication) multiplied by a fraction, the numerator of which is the
number of such class of Company Securities proposed to be sold by the DLJMB
Entities and their Permitted Transferees on behalf of the DLJMB Entities and
their Permitted Transferees and the Other Stockholders and the denominator of
which is the total number of such class of Company Securities on a Fully Diluted
basis beneficially owned by the Stockholders.

     "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.

     "FULLY DILUTED" means, with respect to Common Stock and without
duplication, all outstanding Shares and all Shares issuable in respect of
securities convertible into or exchangeable for Shares, options, warrants
(including the Warrants) and other rights to purchase or subscribe for Shares or
securities convertible into or exchangeable for Common Stock; PROVIDED that, to
the extent any of the foregoing options, warrants or other rights to purchase or
subscribe for


                                       3
<PAGE>

Shares are subject to vesting, the Shares subject to vesting shall be included
in the definition of "FULLY DILUTED" only upon and to the extent of such
vesting; and PROVIDED FURTHER that any Shares that vest upon and as a result of
a certain transaction shall be included in the definition of "FULLY DILUTED" for
purposes of such transaction.

     "HIGH YIELD WARRANTS" means the warrants to purchase an aggregate of
591,366 Shares (on a pre-Exchange basis) that were issued to purchasers of the
Senior Subordinated Notes of Charles River Laboratories, Inc. on or around the
Closing Date.

     "INITIAL OWNERSHIP" means, with respect to any Stockholder and any class of
Company Securities, the number of shares of such class of Company Securities
beneficially owned by such Person and (without duplication) which such Person
had the right to acquire (i) as of September 29, 1999 or (ii) in the case of any
Person that became or shall become a party to this Agreement on a later date, as
of such date, in each case taking into account any stock split, stock dividend,
reverse stock split or similar event; PROVIDED that in the case of any
Stockholder that was a party to the Original Agreement and received Shares in
the Distribution, such Shares shall be included as Company Securities for
purposes of determining such Stockholder's "Initial Ownership."

     "INITIAL PUBLIC OFFERING" means the first sale after the date hereof of
Common Stock pursuant to an effective registration statement under the
Securities Act (other than (1) a registration statement on Form S-8 or any
successor form and (2) a shelf registration statement filed with respect to the
High Yield Warrants and / or Warrants).

     "OTHER STOCKHOLDERS" means all Stockholders other than the DLJMB Entities
and their Permitted Transferees; PROVIDED that DLJIP, BB, Carlyle, and the TCW
Entities shall be considered for purposes of this Agreement to be Other
Stockholders.

     "PERMITTED TRANSFEREE" means:

               (i) in the case of the LLC or any DLJMB Entity: (A) any of: DLJ
          Merchant Banking Partners II, L.P., a Delaware limited partnership,
          DLJ Offshore Partners II, C.V. a Netherlands Antilles limited
          partnership, DLJ Merchant Banking Partners II-A, L.P., a Delaware
          limited partnership, DLJ Diversified Partners, L.P., a Delaware
          limited partnership, DLJ Diversified Partners-A, L.P., a Delaware
          limited partnership, DLJ EAB Partners, L.P., a Delaware limited
          partnership, DLJ Millennium Partners, L.P., a Delaware


                                       4
<PAGE>

          limited partnership, DLJ Millennium Partners-A, L.P., a Delaware
          limited partnership, DLJMB Funding II, Inc., a Delaware corporation,
          UK Investment Plan 1997 Partners, a Delaware partnership, DLJ First
          ESC, L.P., a Delaware limited partnership and DLJ ESC II, L.P., a
          Delaware limited partnership, (each of the foregoing, a "DLJ ENTITY",
          and collectively, the "DLJ ENTITIES"), (B) any general or limited
          partner of any DLJ Entity (a "DLJ PARTNER"), and any corporation,
          partnership, Affiliated Employee Benefit Trust or other entity that is
          an Affiliate of any DLJ Partner (collectively, the "DLJ AFFILIATES"),
          (C) any managing director, general partner, director, limited partner,
          officer or employee of any DLJ Entity or of any DLJ Affiliate, or the
          heirs, executors, administrators, testamentary trustees, legatees or
          beneficiaries of any of the foregoing persons referred to in this
          clause (C) (collectively, "DLJ ASSOCIATES"), (D) a trust, the
          beneficiaries of which, or a corporation, limited liability company or
          partnership, the stockholders, members or general or limited partners
          of which, include only DLJ Entities, DLJ Affiliates, DLJ Associates,
          their spouses or their lineal descendants, or (E) a voting trustee for
          one or more DLJ Entities, DLJ Affiliates or DLJ Associates; PROVIDED
          that notwithstanding the foregoing, no Other Stockholder shall be a
          Permitted Transferee of a DLJMB Entity;

               (ii) in the case of CRL, Bausch & Lomb Incorporated ("B&L"), or
          any wholly-owned subsidiary of B&L; and

               (iii) in the case of any Management Stockholder: (A) a Person to
          whom Shares are transferred from such Other Stockholder (1) by will or
          the laws of descent and distribution or (2) by gift without
          consideration of any kind; PROVIDED that, in the case of clause (2),
          such transferee is the issue or spouse of such Management Stockholder,
          (B) a trust that is for the exclusive benefit of such Management
          Stockholder or its Permitted Transferees under (A) above, or a
          custodian or guardian for the exclusive benefit of the same, or (C)
          the Company, in a transfer approved by the Board; and

               (iv) in the case of DLJIP, BB, Carlyle, and the TCW Entities: any
          Affiliate of such Person.

     "PERSON" means an individual, corporation, partnership, association, trust
or other entity or organization, including a government or political subdivision
or an agency or instrumentality thereof.


                                       5
<PAGE>

     "PRO RATA PORTION" means the number of Shares a Stockholder holds
multiplied by a fraction, the numerator of which is the number of Shares to be
sold collectively by the DLJMB Entities and their Permitted Transferees in a
Public Offering and the denominator of which is the total number of Shares, on a
Fully Diluted basis, held in the aggregate by the DLJMB Entities and their
Permitted Transferees prior to such Public Offering (excluding any Shares
acquired or acquirable upon the exercise of High Yield Warrants).

     "PUBLIC OFFERING" means an underwritten public offering of Registrable
Securities of the Company pursuant to an effective registration statement under
the Securities Act.

     "REGISTRABLE SECURITIES" means any Shares or Warrants until (i) a
registration statement covering such Shares or Warrants has been declared
effective by the SEC and such Shares or Warrants have been disposed of pursuant
to such effective registration statement, (ii) such Shares or Warrants are sold
under circumstances in which all of the applicable conditions of Rule 144 are
met, or (iii) such Shares or Warrants are otherwise transferred, the Company has
delivered a new certificate or other evidence of ownership for such Shares or
Warrants not bearing the legend required pursuant to this Agreement and such
Shares or Warrants may be resold without subsequent registration under the
Securities Act, PROVIDED that the term "Registrable Securities" shall not apply
to any Shares received upon exercise of any High Yield Warrants.

     "REGISTRATION EXPENSES" means (i) all registration and filing fees, (ii)
fees and expenses of compliance with securities or blue sky laws (including
reasonable fees and disbursements of counsel in connection with blue sky
qualifications of the Shares or Warrants), (iii) printing expenses, (iv)
internal expenses of the Company (including, without limitation, all salaries
and expenses of its officers and employees performing legal or accounting
duties), (v) reasonable fees and disbursements of counsel for the Company and
customary fees and expenses for independent certified public accountants
retained by the Company (including the expenses of any comfort letters or costs
associated with the delivery by independent certified public accountants of a
comfort letter or comfort letters requested pursuant to Section 5.04(h)), (vi)
the reasonable fees and expenses of any special experts retained by the Company
in connection with such registration, (vii) reasonable fees and expenses of one
counsel for the Stockholders participating in the offering selected (A) by the
DLJMB Entities, in the case of any offering in which the DLJMB Entities or any
Permitted Transferee of the DLJMB Entities participates, or (B) in any other
case, by the Other Stockholders holding the majority of Shares to be sold for
the account of all Other Stockholders in the offering, (viii) fees and expenses
in connection with any review of underwriting arrangements by the National
Association of Securities Dealers, Inc.


                                       6
<PAGE>

(the "NASD") including fees and expenses of any "QUALIFIED INDEPENDENT
UNDERWRITER" and (ix) fees and disbursements of underwriters customarily paid by
issuers or sellers of securities; but shall not include any underwriting fees,
discounts or commissions attributable to the sale of Registrable Securities, or
any out-of-pocket expenses (except as set forth in clause (vii) above) of the
Stockholders (or the agents who manage their accounts) or any fees and expenses
of underwriter's counsel.

     "RESTRICTION TERMINATION DATE" means the earlier to occur of (a) the second
anniversary of the Initial Public Offering and (b) the fifth anniversary of the
Closing Date.

     "RULE 144" means Rule 144 and Rule 144A (or any successor provisions) under
the Securities Act.

     "SEC" means the Securities and Exchange Commission.

     "SECURITIES ACT" means the Securities Act of 1933, as amended.

     "SHARES" means shares of Common Stock.

     "STOCKHOLDER" means each Person (other than the Company) who shall be a
party to or bound by this Agreement, whether in connection with the execution
and delivery hereof as of the date hereof, pursuant to Section 6.05, or
otherwise, so long as such Person shall (i) beneficially own (directly or
indirectly) any Company Securities, or (ii) have any stock appreciation rights,
options, warrants (other than High Yield Warrants) or other rights to purchase
or subscribe for Company Securities.

     "SUBJECT SECURITIES" means any Company Securities beneficially owned by the
Other Stockholders.

     "TCW ENTITIES" means TCW/Crescent Mezzanine Partners II, L.P., TCW/Crescent
Mezzanine Trust II, Crescent/MACH I Partners, L.P., TCW Leveraged Income Trust,
L.P. and TCW Leveraged Income Trust II, L.P.

     "THIRD PARTY" means a prospective purchaser of Shares in an arm's-length
transaction from a Stockholder where such purchaser is not a Permitted
Transferee of such Stockholder.

     "WARRANTS" means the warrants issued by the Company to the DLJ Entities for
the purchase of shares of Common Stock constituting not more than 10% (the
"AGREED PERCENTAGE") of the fully diluted equity of the Company,


                                       7
<PAGE>

PROVIDED that the Agreed Percentage shall be subject to adjustment in the event
of any disruption or adverse change in current financial or capital markets
generally or in the market for new issuances of high yield securities.

     "WARRANT SHARES" means shares of Common Stock issuable by the Company upon
exercise of the Warrants.

     (b) The term "LLC", to the extent the LLC shall transfer any of its Shares
after the date hereof to "Permitted Transferees", shall mean the LLC and the
Permitted Transferees of the LLC, taken together, and any right or action that
may be taken at the election of the LLC may be taken at the election of the
holders of a majority of the Shares then held by the LLC and such Permitted
Transferees.

     (c) The term "Other Stockholders", to the extent such stockholders shall
have transferred any of their Shares to "Permitted Transferees", shall mean the
Other Stockholders and the Permitted Transferees of the Other Stockholders,
taken together, and any right or action that may be taken at the election of the
Other Stockholders may be taken at the election of the Other Stockholders and
such Permitted Transferees.

     (d) Each of the following terms is defined in the Section set forth
opposite such term:

<TABLE>

<CAPTION>

TERM                                                   SECTION
----                                                   -------
<S>                                                    <C>
Applicable Holdback Period                             5.03
beneficially own                                       1.01(a)
Demand Registration                                    5.01(e)
DLJSC                                                  6.03
Drag-Along Rights                                      4.01(a)
Holders                                                5.01(a)
Incidental Registration                                5.01(e)
Indemnified Party                                      5.07
Indemnifying Party                                     5.07
Inspectors                                             5.04(g)
Maximum Offering Size                                  5.01(e)
Nominee                                                2.03(a)
Records                                                5.04(g)
Section 4.01 Notice                                    4.01(a)
Section 4.01 Notice Period                             4.01(a)
Section 4.01 Sale                                      4.01(a)
Section 4.01 Sale Price                                4.01(a)

</TABLE>


                                       8
<PAGE>

<TABLE>

<CAPTION>

TERM                                                   SECTION
----                                                   -------
<S>                                                    <C>
Selling Stockholder                                    5.01(e)
Transfer                                               3.01(a)

</TABLE>

                                    ARTICLE 2
                              CORPORATE GOVERNANCE

     SECTION 2.01. COMPOSITION OF THE BOARD. (a) The Board shall consist of at
least nine but no more than 12 directors, (i) seven of whom (including the
Chairman) will be designated by DLJ Merchant Banking Partners II, L.P., (ii) one
of whom will be designated by CRL, (iii) one of whom will be the Chief Executive
Officer appointed by the Board and (iv) any additional of whom will be
designated by a vote of a majority of the other directors. DLJIP shall be
entitled to designate one observer to the Board, who shall be entitled to
receive a copy of any materials distributed to all members of the Board, until
the date on which DLJIP owns (directly or indirectly) less than 50% of the
equity interest in the Company which it owned (indirectly) as of the Closing
Date.

     (b) Each Stockholder (other than CRL) entitled to vote for the election of
directors to the Board agrees that it will vote its Shares or execute written
consents, as the case may be, and take all other necessary action (including
causing the Company to call a special meeting of stockholders) in order to
ensure that the composition of the Board is as set forth in this Section 2.01;
PROVIDED that no Other Stockholder shall be required to vote for the
board-designees of DLJ Merchant Banking Partners II, L.P. if the aggregate
number of Common Shares held collectively by the DLJMB Entities is less than 10%
of their collective Initial Ownership of Common Shares, and PROVIDED FURTHER
that no party hereto shall be required to vote for the board-designee of CRL if
the aggregate number of Common Shares held by CRL is less than 40% of the
Initial Ownership of CRL.

     SECTION 2.02. REMOVAL. Each Stockholder (other than CRL) agrees that if, at
any time, it is then entitled to vote for the removal of directors of the
Company, it will not vote any of its Shares in favor of the removal of any
director who shall have been designated or nominated pursuant to Section 2.01
unless such removal shall be for cause or the Persons entitled to designate or
nominate such director shall have consented to such removal in writing.

     SECTION 2.03. VACANCIES. If, as a result of death, disability, retirement,
resignation, removal (with or without cause) or otherwise, there shall exist or
occur any vacancy of the Board:


                                       9
<PAGE>

     (a) the Person or Persons entitled under Section 2.01 to designate or
nominate such director whose death, disability, retirement, resignation or
removal resulted in such vacancy may designate another individual (the
"NOMINEE") to fill such capacity and serve as a director of the Company; and

     (b) each Stockholder (other than CRL) then entitled to vote for the
election of the Nominee as a director of the Company agrees that it will vote
its Shares, or execute a written consent, as the case may be, in order to ensure
that the Nominee is elected to the Board.

     SECTION 2.04. MEETINGS. The Board shall hold a regularly scheduled meeting
at least once every calendar quarter, and notice of each meeting shall be given
to all directors at least five Business Days prior to such meeting.

     SECTION 2.05. ACTION BY THE BOARD. (a) A quorum of the Board shall consist
of four directors, of whom at least three must be designees of DLJ Merchant
Banking Partners II, L.P.; PROVIDED that DLJ Merchant Banking Partners II, L.P.
shall have the right at any time to change the number of directors necessary to
constitute a quorum of the Board. All actions of the Board shall require the
affirmative vote of at least a majority of the directors present at a duly
convened meeting of the Board at which a quorum is present or the unanimous
written consent of the Board; PROVIDED that, in the event there is a vacancy on
the Board and an individual has been nominated to fill such vacancy, the first
order of business shall be to fill such vacancy.

     (b) CRL shall have the right to send an observer who is an employee of B&L
or an Affiliate of B&L to any meeting of the Board that the director who is
designated by CRL is unable to attend. The observer shall have the privilege of
voice but no vote with respect to any matter and shall be given a copy of any
materials distributed to the Board members for such meeting.

     (c) The Board may create executive, compensation and audit committees, as
well as such other committees as it may determine. DLJ Merchant Banking Partners
II, L.P. shall be entitled to designate a majority of the directors on any
committee created by the Board.

     SECTION 2.06. CONFLICTING CHARTER OR BYLAW PROVISIONS. Each Stockholder
shall vote its Shares or execute written consents, as the case may be, and take
all other actions necessary, to ensure that the Company's Charter and Bylaws
facilitate and do not at any time conflict with any provision of this Agreement.


                                       10
<PAGE>

                                    ARTICLE 3
                            RESTRICTIONS ON TRANSFER

     SECTION 3.01. GENERAL. (a) Each Stockholder understands and agrees that the
Company Securities purchased pursuant to the applicable subscription agreement
have not been registered under the Securities Act and are restricted securities.
Each Stockholder agrees that it will not, directly or indirectly, sell, assign,
transfer, grant a participation in, pledge or otherwise dispose of ("TRANSFER")
any Company Securities (or solicit any offers to buy or otherwise acquire, or
take a pledge of any Company Securities) except in compliance with the
Securities Act and the terms and conditions of this Agreement.

     (b) Any attempt to transfer any Company Securities not in compliance with
this Agreement shall be null and void and the Company shall not, and shall cause
any transfer agent not to, give any effect in the Company's stock records to
such attempted transfer.

     (c) No transferee other than a Permitted Transferee or a party hereto shall
be required or permitted to become a party to this Agreement or have the benefit
of any rights hereunder or the burden of any obligations hereunder.

     (d) Except as set forth in the first sentence of Section 3.01(a), transfers
by the DLJMB Entities are not subject to any restrictions.

     SECTION 3.02. LEGENDS. In addition to any other legend that may be
required, each certificate for shares of Common Stock and each Warrant that is
issued to any Stockholder shall bear a legend in substantially the following
form:

     "THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY STATE SECURITIES LAWS AND MAY NOT BE OFFERED OR SOLD EXCEPT IN
COMPLIANCE THEREWITH. THIS SECURITY IS ALSO SUBJECT TO ADDITIONAL RESTRICTIONS
ON TRANSFER AS SET FORTH IN THE INVESTORS' AGREEMENT DATED AS OF SEPTEMBER 29,
1999, AS AMENDED AND RESTATED ON JUNE 19, 2000, COPIES OF WHICH MAY BE OBTAINED
UPON REQUEST FROM CHARLES RIVER LABORATORIES INTERNATIONAL, INC. OR ANY
SUCCESSOR THERETO."

     If any Company Securities shall cease to be Registrable Securities under
clause (i) or clause (ii) of the definition thereof, the Company shall, upon the
written request of the holder thereof, issue to such holder a new certificate
evidencing such securities without the first sentence of the legend required by
this Section endorsed thereon. If any Company Securities cease to be subject to
any


                                       11
<PAGE>

and all restrictions on transfer set forth in this Agreement, the Company shall,
upon the written request of the holder thereof, issue to such holder a new
certificate evidencing such Company Securities without the second sentence of
the legend required by this Section endorsed thereon.

     SECTION 3.03. PERMITTED TRANSFEREES. Notwithstanding anything in this
Agreement to the contrary, any Stockholder may at any time transfer any or all
of its Company Securities to one or more of its Permitted Transferees without
the consent of the Board or any other Stockholder or group of Stockholders and
without compliance with Sections 3.04, 3.05, and 3.06 so long as (a) such
Permitted Transferee shall have agreed in writing to be bound by the terms of
this Agreement and (b) the transfer to such Permitted Transferee is not in
violation of applicable federal or state securities laws.

     SECTION 3.04. RESTRICTIONS ON TRANSFERS BY MANAGEMENT STOCKHOLDERS.

     (a) Each Management Stockholder and each Permitted Transferee of such
Management Stockholder may transfer its Company Securities only as follows:

          (i) in a transfer made in compliance with Section 4.01;

          (ii) subject to the Public Offering Limitations, in a Public Offering
     in connection with the exercise of its rights under Article 5 hereof;

          (iii) after the Initial Public Offering, pursuant to a registration
     statement on Form S-8 (or any successor form) or pursuant to the exemption
     from registration provided under Rule 144, PROVIDED that until the later of
     (A) the third anniversary of the IPO and (B) the Restriction Termination
     Date, such sales cannot reduce the Stockholder's ownership to (or occur at
     a time when such Stockholder's ownership is otherwise) below the greater of
     (X) 50% of his or her Initial Ownership and (Y) that percentage of his or
     her Initial Ownership as equals the percentage of the DLJMB Entities'
     collective Initial Ownership remaining after previous dispositions by the
     DLJMB Entities; or

          (iv) following the Restriction Termination Date, to (A) any Third
     Party other than an Adverse Person or any person deemed inappropriate by
     the Board or (B) any Third Party through a national securities exchange, in
     each case for consideration consisting solely of cash, PROVIDED, however,
     that the amount sold in any 12-month period may not exceed 20% of the


                                       12
<PAGE>

     Company Securities beneficially owned by such Management Stockholder on the
     date of the Initial Public Offering.

     For purposes of this Agreement, "PUBLIC OFFERING LIMITATIONS" means (A) no
Management Stockholder shall be permitted to sell any Shares in the Initial
Public Offering, (B) in the first public offering following the Initial Public
Offering, no Management Stockholder may sell more than the lesser of (x) 50% of
his or her Pro Rata Portion and (y) 20% of his or her holdings prior to the
offering and (C) in each public offering thereafter, each Management Stockholder
may sell no more than the lesser of (x) his or her Pro Rata Portion and (y) 50%
of his or her holdings prior to the offering.

     (b) The provisions of Section 3.04(a) shall terminate upon the earliest to
occur of (i) the tenth anniversary of the Closing Date and (ii) the date upon
which the collective shareholdings of the DLJMB Entities fall below 10% of their
collective Initial Ownership. Notwithstanding the foregoing sentence, the
provisions of Section 3.04(a) shall not terminate with respect to any Management
Stockholder's Shares which shall have been pledged to the Company as security in
connection with any indebtedness for borrowed money owed by such Management
Stockholder to the Company unless the proceeds from the sale of such Shares are
applied to repay such indebtedness in full.

     SECTION 3.05. RESTRICTIONS ON TRANSFERS BY CRL.

     (a) CRL may transfer its Company Securities only as follows:

          (i) in a transfer made in compliance with Section 4.01;

          (ii) in a Public Offering in connection with the exercise of its
     rights under Article 5 hereof;

          (iii) after the Initial Public Offering, pursuant to the exemption
     from registration provided under Rule 144, PROVIDED, however, that the
     amount sold in any 12-month period pursuant to this clause (iii) may not
     exceed 25% of CRL's Initial Ownership.

          (iv) following the Restriction Termination Date, to (A) any Third
     Party other than an Adverse Person or any person deemed inappropriate by
     the Board or (B) any Third Party through a national securities exchange, in
     each case for consideration consisting solely of cash.

     (b) The provisions of Section 3.05(a) shall terminate upon the earliest to
occur of (i) the tenth anniversary of the Closing Date and (ii) the date upon
which


                                       13
<PAGE>

the collective shareholdings of the DLJMB Entities fall below 10% of their
collective Initial Ownership.

     SECTION 3.06. RESTRICTIONS ON TRANSFERS BY NEW MINORITY SHAREHOLDERS.

     (a) Each of DLJIP, BB, Carlyle, and the TCW Entities (a "NEW MINORITY
SHAREHOLDER") may transfer its Company Securities only as follows:

          (i) in a transfer made in compliance with Section 4.01;

          (ii) in a Public Offering in connection with the exercise of its
     rights under Article 5 hereof;

          (iii) after the Initial Public Offering, pursuant to the exemption
     from registration provided under Rule 144;

          (iv) after the earlier of (A) three years from the Closing Date or (B)
     the Initial Public Offering, to any Third Party other than an Adverse
     Person or any person deemed inappropriate by the Board; or

          (v) to the limited partners of such New Minority Shareholder, as part
     of a general distribution of all assets held by such New Minority
     Shareholder to its limited partners; PROVIDED that any transferees pursuant
     to this clause (v) shall be deemed not to be Permitted Transferees.

     (b) The provisions of Section 3.06(a) shall terminate upon the earliest to
occur of (i) the tenth anniversary of the Closing Date and (ii) the date upon
which the collective shareholdings of the DLJMB Entities fall below 10% of their
collective Initial Ownership.

                                    ARTICLE 4

                                DRAG-ALONG RIGHTS

         SECTION 4.01. RIGHT TO COMPEL PARTICIPATION IN CERTAIN TRANSFERS. (a)
If (i) the DLJMB Entities collectively propose to transfer not less than 50% of
their collective Initial Ownership of Common Stock to a Third Party in a bona
fide sale or (ii) the DLJMB Entities propose an arms-length transfer in which
the shares of Common Stock to be transferred by the DLJMB Entities and their
Permitted Transferees constitute more than 50% of the outstanding shares of
Common Stock (a "SECTION 4.01 SALE"), the DLJMB Entities may at their option
require all Other Stockholders to sell the Drag-Along Portion of the Subject
Securities ("DRAG-


                                       14
<PAGE>

ALONG RIGHTS") then held by every Other Stockholder, and (subject to and at the
closing of the Section 4.01 Sale) to exercise all, but not less than all, of the
options held by every Other Stockholder and to sell all of the shares of Common
Stock received upon such exercise to such Third Party, for the same
consideration per share of Common Stock and otherwise on the same terms and
conditions as the DLJMB Entities; PROVIDED that any Other Stockholder who holds
options the exercise price per share of which is greater than the per share
price at which the Shares are to be sold to the Third Party may, if required by
the DLJMB Entities to exercise such options, in place of such exercise, submit
to irrevocable cancellation thereof without any liability for payment of any
exercise price with respect thereto. In the event the Section 4.01 Sale is not
consummated with respect to any shares acquired upon exercise of such options,
or the Section 4.01 Sale is not consummated, such options shall be deemed not to
have been exercised or canceled, as applicable. The DLJMB Entities shall provide
written notice of such Section 4.01 Sale to the Other Stockholders (a "SECTION
4.01 NOTICE") not later than the 15th Business Day prior to the proposed Section
4.01 Sale. The Section 4.01 Notice shall identify the transferee, the number of
Subject Securities, the consideration for which a transfer is proposed to be
made (the "SECTION 4.01 SALE PRICE") and all other material terms and conditions
of the Section 4.01 Sale. The number of shares of Common Stock to be sold by
each Other Stockholder will be the Drag-Along Portion of the shares of Common
Stock that such Other Stockholder owns. Each Other Stockholder shall be required
to participate in the Section 4.01 Sale on the terms and conditions set forth in
the Section 4.01 Notice and to tender all its Subject Securities as set forth
below. The price payable in such transfer shall be the Section 4.01 Sale Price.
Not later than the 10th Business Day following the date of the Section 4.01
Notice (the "SECTION 4.01 NOTICE PERIOD"), each of the Other Stockholders shall
deliver to a representative of the DLJMB Entities designated in the Section 4.01
Notice certificates representing all Subject Securities representing the Drag
Along Portion held by such Other Stockholder, duly endorsed, together with all
other documents required to be executed in connection with such Section 4.01
Sale. If an Other Stockholder should fail to deliver such certificates to the
representative of the DLJMB Entities, the Company shall cause the books and
records of the Company to show that such Subject Securities are bound by the
provisions of this Section 4.01 and that such Subject Securities shall be
transferred to the purchaser of the Subject Securities immediately upon
surrender for transfer by the holder thereof.

     (b) The DLJMB Entities shall have a period of 45 days from the date of
receipt of the Section 4.01 Notice to consummate the Section 4.01 Sale on the
terms and conditions set forth in such Section 4.01 Sale Notice. If the Section
4.01 Sale shall not have been consummated during such period, the DLJMB Entities
shall return to each of the Other Stockholders all certificates representing
Subject Securities that such Other Stockholder delivered for transfer pursuant


                                       15
<PAGE>

hereto, together with any documents in the possession of the DLJMB Entities
executed by the Other Stockholder in connection with such proposed transfer, and
all the restrictions on transfer contained in this Agreement or otherwise
applicable at such time with respect to Common Stock owned by the Other
Stockholders shall again be in effect.

     (c) Concurrently with the consummation of the transfer of Company
Securities pursuant to this Section 4.01, the DLJMB Entities shall give notice
thereof to all Stockholders, shall remit to each of the Stockholders who have
surrendered their certificates the total consideration (by bank or certified
check) for the Subject Securities transferred pursuant hereto and shall furnish
such other evidence of the completion and time of completion of such transfer
and the terms thereof as may be reasonably requested by such Stockholders.

                                    ARTICLE 5

                               REGISTRATION RIGHTS

     SECTION 5.01. DEMAND REGISTRATION. (a) If the Company shall receive a
written request by the DLJMB Entities or their Permitted Transferees or DLJIP
(any such requesting Person, a "SELLING STOCKHOLDER") that the Company effect
the registration under the Securities Act of all or a portion of such Selling
Stockholder's Registrable Securities, and specifying the intended method of
disposition thereof, then the Company shall promptly give written notice of such
requested registration (a "DEMAND REGISTRATION") at least 30 days prior to the
anticipated filing date of the registration statement relating to such Demand
Registration to the Other Stockholders and thereupon will use its best efforts
to effect, as expeditiously as possible, the registration under the Securities
Act of:

          (i) the Registrable Securities which the Company has been so requested
     to register by the Selling Stockholders, then held by the Selling
     Stockholders; and

          (ii) subject to the restrictions set forth in Section 5.01(e), all
     other Registrable Securities of the same type as that to which the request
     by the Selling Stockholders relates which any Other Stockholder entitled to
     request the Company to effect an Incidental Registration (as such term is
     defined in Section 5.02) pursuant to Section 5.02 (all such Stockholders,
     together with the Selling Stockholders, the "HOLDERS") has requested the
     Company to register by written request received by the Company within 15
     days after the receipt by such Holders of such written notice given by the
     Company,


                                       16
<PAGE>

all to the extent necessary to permit the disposition (in accordance with the
intended methods thereof as aforesaid) of the Registrable Securities so to be
registered; PROVIDED that, subject to Section 5.01(d) hereof, the Company shall
not be obligated to effect more than (A) six Demand Registrations for the DLJMB
Entities and their Permitted Transferees or (B) one Demand Registration for
DLJIP (which Demand Registration right may not be exercised prior to the earlier
of (1) five years from the Closing Date and (2) the date that is 180 days after
an Initial Public Offering); and PROVIDED FURTHER that the Company shall not be
obligated to effect a Demand Registration unless the aggregate proceeds expected
to be received from the sale of the Common Stock to be included in such Demand
Registration, in the reasonable opinion of DLJ Merchant Banking II, Inc.
exercised in good faith, equals or exceeds (Y) $30,000,000 if such Demand
Registration would constitute the Initial Public Offering, or (Z) $10,000,000 in
all other cases. In no event will the Company be required to effect more than
one Demand Registration within any four-month period.

     (b) Promptly after the expiration of the 15-day period referred to in
Section 5.01(a)(ii) hereof, the Company will notify all the Holders to be
included in the Demand Registration of the other Holders and the number of
Registrable Securities requested to be included therein. The Selling
Stockholders requesting a registration under this Section may, at any time prior
to the effective date of the registration statement relating to such
registration, revoke such request, without liability to any of the other
Holders, by providing a written notice to the Company revoking such request, in
which case such request, so revoked, shall be considered a Demand Registration
unless the participating Stockholders reimburse the Company for all costs
incurred by the Company in connection with such registration, or unless such
revocation arose out of the fault of the Company, in which case such request
shall not be considered a Demand Registration.

     (c) The Company will pay all Registration Expenses in connection with any
Demand Registration.

     (d) A registration requested pursuant to this Section shall not be deemed
to have been effected (i) unless the registration statement relating thereto (A)
has become effective under the Securities Act and (B) has remained effective for
a period of at least 180 days (or such shorter period in which all Registrable
Securities of the Holders included in such registration have actually been sold
thereunder); PROVIDED that if after any registration statement requested
pursuant to this Section becomes effective (x) such registration statement is
interfered with by any stop order, injunction or other order or requirement of
the SEC or other governmental agency or court and (y) less than 75% of the
Registrable Securities included in such registration statement has been sold
thereunder, such registration


                                       17
<PAGE>

statement shall not be considered a Demand Registration or (ii) if the Maximum
Offering Size (as defined below) is reduced in accordance with Section 5.01(e)
or 5.01(f) such that less than 66 2/3% of the Registrable Securities of the
Selling Stockholders sought to be included in such registration are included.

     (e) If a Demand Registration involves an Underwritten Public Offering and
the managing underwriter shall advise the Company and the Selling Stockholders
that, in its view, (i) the number of Registrable Securities requested to be
included in such registration (including any securities which the Company
proposes to be included which are not Registrable Securities) or (ii) the
inclusion of some or all of the Registrable Securities owned by the Holders, in
any such case, exceeds the largest number of securities which can be sold
without having an adverse effect on such offering, including the price at which
such securities can be sold (the "MAXIMUM OFFERING SIZE"), the Company will
include in such registration, in the priority listed below, up to the Maximum
Offering Size:

               (A) first: (1) in the case of a Demand by the DLJMB Entities and
          their Permitted Transferees, all Securities requested to be registered
          by the Selling Stockholder and by all of its Permitted Transferees and
          CRL, DLJIP, BB, Carlyle, and the TCW Entities (allocated, if necessary
          for the offering not to exceed the Maximum Offering Size, PRO RATA
          among such Persons on the basis of the relative number of shares of
          Registrable Securities requested to be registered), or (2) in the case
          of a Demand by DLJIP, all Securities requested to be registered by the
          Selling Stockholder and by all of its Permitted Transferees and BB,
          Carlyle, ESC II and the TCW Entities (allocated, if necessary for the
          offering not to exceed the Maximum Offering Size, PRO RATA among such
          Persons on the basis of the relative number of shares of Registrable
          Securities requested to be registered);

               (B) second: (1) in the case of a Demand by the DLJMB Entities and
          their Permitted Transferees, all Registrable Securities requested to
          be included in such registration by any other Holder (allocated, if
          necessary for the offering not to exceed the Maximum Offering Size,
          PRO RATA among such other Holders on the basis of the relative number
          of shares of Registrable Securities requested to be included in such
          registration), or (2) in the case of a Demand by DLJIP, all
          Registrable Securities requested to be included in such registration
          by the DLJMB Entities (other than ESC II) and their Permitted
          Transferees and by CRL (allocated, if necessary for the offering not
          to exceed the Maximum Offering Size, PRO RATA among such other Holders
          on the basis of the relative number of


                                       18
<PAGE>

          shares of Registrable Securities requested to be included in such
          registration);

               (C) third: (1) in the case of a Demand by the DLJMB Entities and
          their Permitted Transferees, any securities proposed to be registered
          by the Company, or (2) in the case of a Demand by DLJIP, all
          Registrable Securities requested to be included in such registration
          by any other Holder (allocated, if necessary for the offering not to
          exceed the Maximum Offering Size, PRO RATA among such other Holders on
          the basis of the relative number of shares of Registrable Securities
          requested to be included in such registration); and

               (D) fourth: in the case of a Demand by DLJIP, any securities
          proposed to be registered by the Company.

     (f) If the Company files a shelf registration statement with respect to the
High Yield Warrants, the Company shall notify the holders of the Warrants at
least 20 days prior to such filing. The holders of the Warrants shall have the
right (which shall not be deemed to be a use of a Demand Registration right), by
notice to the Company, to include the Warrants in such shelf registration
statement. Notwithstanding anything in this Agreement to the contrary, this
Agreement shall not be construed to confer on any Stockholder (other than
holders of Warrants in their capacity as such, together with any Persons
entitled to indemnification hereunder in connection therewith) any rights in
connection with such shelf registration statement.

     SECTION 5.02. INCIDENTAL REGISTRATION. (a) If the Company proposes to
register any Company Securities under the Securities Act (other than a
registration (A) on Form S-8 or S-4 or any successor or similar forms, (B)
relating to Common Stock issuable upon exercise of employee stock options or in
connection with any employee benefit or similar plan of the Company or (C) in
connection with a direct or indirect acquisition by the Company of another
company), whether or not for sale for its own account, it will each such time,
subject to the provisions of Section 5.02(b), give prompt written notice at
least 30 days prior to the anticipated filing date of the registration statement
relating to such registration to the DLJMB Entities and each Other Stockholder,
which notice shall set forth such Stockholder's rights under this Section 5.02
and shall offer such Stockholders the opportunity to include in such
registration statement such number of Registrable Securities of the same type as
are proposed to be registered as each such Stockholder may request (an
"INCIDENTAL REGISTRATION"). Upon the written request of any such Stockholder
made within 15 days after the receipt of notice from the Company (which request
shall specify the number of Registrable


                                       19
<PAGE>

Securities intended to be disposed of by such Stockholder), the Company will use
its best efforts to effect the registration under the Securities Act of all
Registrable Securities which the Company has been so requested to register by
such Stockholders, to the extent requisite to permit the disposition of the
Registrable Securities so to be registered; PROVIDED that (I) if such
registration involves a Public Offering, all such Stockholders requesting to be
included in the Company's registration must sell their Registrable Securities to
the underwriters selected as provided in Section 5.04(f) on the same terms and
conditions as apply to the Company and (II) if, at any time after giving written
notice of its intention to register any stock pursuant to this Section 5.02(a)
and prior to the effective date of the registration statement filed in
connection with such registration, the Company shall determine for any reason
not to register such securities, the Company shall give written notice to all
such Stockholders and, thereupon, shall be relieved of its obligation to
register any Registrable Securities in connection with such registration
(without prejudice, however, to rights of the DLJMB Entities under Section
5.01). No registration effected under this Section 5.02 shall relieve the
Company of its obligations to effect a Demand Registration to the extent
required by Section 5.01. The Company will pay all Registration Expenses in
connection with each registration of Registrable Securities requested pursuant
to this Section 5.02.

     (b) If a registration pursuant to this Section 5.02 involves a Public
Offering (other than in the case of a Public Offering requested by the DLJMB
Entities or any of their Permitted Transferees or the Other Stockholders in a
Demand Registration, in which case the provisions with respect to priority of
inclusion in such offering set forth in Section 5.01(e) shall apply) and the
managing underwriter advises the Company that, in its view, the number of Shares
that the Company and such Stockholders intend to include in such registration
exceeds the Maximum Offering Size, the Company will include in such
registration, in the following priority, up to the Maximum Offering Size:

               (i) first, so much of the securities proposed to be registered by
          the Company as would not cause the offering to exceed the Maximum
          Offering Size;

               (ii) second, all Registrable Securities requested to be included
          in such registration by the DLJMB Entities and their Permitted
          Transferees or any Other Stockholder pursuant to this Section 5.02
          (allocated, if necessary for the offering not to exceed the Maximum
          Offering Size, pro rata among such Stockholders on the basis of the
          relative number of shares of Registrable Securities so requested to be
          included in such registration).


                                       20
<PAGE>

     SECTION 5.03. HOLDBACK AGREEMENTS. If any registration of Registrable
Securities shall be in connection with a Public Offering, the DLJMB Entities and
their Permitted Transferees and each Other Stockholder each agree not to effect
any public sale or distribution, including any sale pursuant to Rule 144, or any
successor provision, under the Securities Act, of any Registrable Securities,
and not to effect any such public sale or distribution of any other Common Stock
of the Company or of any stock convertible into or exchangeable or exercisable
for any Common Stock of the Company (in each case, other than as part of such
Public Offering) during the 14 days prior to the effective date of such
registration statement (except as part of such registration) or during the
period after such effective date equal to the lesser of (i) such period of time
as agreed between such managing underwriter and the Company and (ii) 180 days
(such lesser period, the "APPLICABLE HOLDBACK PERIOD").

     SECTION 5.04. REGISTRATION PROCEDURES. Whenever Stockholders request that
any Registrable Securities be registered pursuant to Section 5.01 or 5.02, the
Company will, subject to the provisions of such Sections, use its best efforts
to effect the registration and the sale of such Registrable Securities in
accordance with the intended method of disposition thereof as quickly as
practicable, and in connection with any such request:

     (a) The Company will as expeditiously as possible prepare and file with the
SEC a registration statement on any form for which the Company then qualifies or
which counsel for the Company shall deem appropriate and which form shall be
available for the sale of the Registrable Securities to be registered thereunder
in accordance with the intended method of distribution thereof, and use its best
efforts to cause such filed registration statement to become and remain
effective for a period of not less than 180 days.

     (b) The Company will, if requested, prior to filing a registration
statement or prospectus or any amendment or supplement thereto, furnish to
participating Stockholder and each underwriter, if any, of the Registrable
Securities covered by such registration statement copies of such registration
statement as proposed to be filed, and thereafter the Company will furnish to
such Stockholder and underwriter, if any, such number of copies of such
registration statement, each amendment and supplement thereto (in each case
including all exhibits thereto and documents incorporated by reference therein),
the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such Stockholder or
underwriter may reasonably request in order to facilitate the disposition of the
Registrable Securities owned by such Stockholder.


                                       21
<PAGE>

     (c) After the filing of the registration statement, the Company will
promptly notify each Stockholder holding Registrable Securities covered by such
registration statement of any stop order issued or threatened by the SEC and
take all reasonable actions required to prevent the entry of such stop order or
to remove it if entered.

     (d) The Company will use its best efforts to (i) register or qualify the
Registrable Securities covered by such registration statement under such other
securities or blue sky laws of such jurisdictions in the United States as any
Stockholder holding such Registrable Securities reasonably (in light of such
Stockholder's intended plan of distribution) requests and (ii) cause such
Registrable Securities to be registered with or approved by such other
governmental agencies or authorities as may be necessary by virtue of the
business and operations of the Company and do any and all other acts and things
that may be reasonably necessary or advisable to enable such Stockholder to
consummate the disposition of the Registrable Securities owned by such
Stockholder; PROVIDED that the Company will not be required to (A) qualify
generally to do business in any jurisdiction where it would not otherwise be
required to qualify but for this paragraph (d), (B) subject itself to taxation
in any such jurisdiction or (C) consent to general service of process in any
such jurisdiction.

     (e) The Company will immediately notify each Stockholder holding such
Registrable Securities, at any time when a prospectus relating thereto is
required to be delivered under the Securities Act, of the occurrence of an event
requiring the preparation of a supplement or amendment to such prospectus so
that, as thereafter delivered to the purchasers of such Registrable Securities,
such prospectus will not contain an untrue statement of a material fact or omit
to state any material fact required to be stated therein or necessary to make
the statements therein not misleading and promptly prepare and make available to
each such Stockholder any such supplement or amendment.

     (f) The DLJMB Entities will have the right, in their sole discretion, to
select an underwriter or underwriters in connection with any Public Offering,
which underwriter or underwriters may include any Affiliate of any DLJ Entity.
In connection with any Public Offering, the Company will enter into customary
agreements (including an underwriting agreement in customary form) and take such
other actions as are reasonably required in order to expedite or facilitate the
disposition of Registrable Securities in any such Public Offering, including the
engagement of a "qualified independent underwriter" in connection with the
qualification of the underwriting arrangements with the NASD.


                                       22
<PAGE>

     (g) Upon the execution of confidentiality agreements in form and substance
satisfactory to the Company, the Company will make available for inspection by
any Stockholder and any underwriter participating in any disposition pursuant to
a registration statement being filed by the Company pursuant to this Section
5.04 and any attorney, accountant or other professional retained by any such
Stockholder or underwriter (collectively, the "INSPECTORS"), all financial and
other records, pertinent corporate documents and properties of the Company
(collectively, the "RECORDS") as shall be reasonably necessary to enable them to
exercise their due diligence responsibility, and cause the Company's officers,
directors and employees to supply all information reasonably requested by any
Inspectors in connection with such registration statement. Records that the
Company determines, in good faith, to be confidential and that it notifies the
Inspectors are confidential shall not be disclosed by the Inspectors unless (i)
the disclosure of such Records is necessary to avoid or correct a misstatement
or omission in such registration statement or (ii) the release of such Records
is ordered pursuant to a subpoena or other order from a court of competent
jurisdiction. Each Stockholder agrees that information obtained by it as a
result of such inspections shall be deemed confidential and shall not be used by
it as the basis for any market transactions in the Company Securities or its
Affiliates unless and until such is made generally available to the public. Each
Stockholder further agrees that it will, upon learning that disclosure of such
Records is sought in a court of competent jurisdiction, give notice to the
Company and allow the Company, at its expense, to undertake appropriate action
to prevent disclosure of the Records deemed confidential.

     (h) The Company will furnish to each such Stockholder and to each such
underwriter, if any, a signed counterpart, addressed to such underwriter, of (i)
an opinion or opinions of counsel to the Company and (ii) a comfort letter or
comfort letters from the Company's independent public accountants, each in
customary form and covering such matters of the type customarily covered by
opinions or comfort letters, as the case may be, as a majority of such
Stockholders or the managing underwriter therefor reasonably requests.

     (i) The Company will otherwise use its best efforts to comply with all
applicable rules and regulations of the SEC, and make available to its
stockholders, as soon as reasonably practicable, an earnings statement covering
a period of 12 months, beginning within three months after the effective date of
the registration statement, which earnings statement shall satisfy the
provisions of Section 11(a) of the Securities Act.

     The Company may require each such Stockholder to promptly furnish in
writing to the Company such information regarding the distribution of the
Registrable Securities as the Company may from time to time reasonably request


                                       23
<PAGE>

and such other information as may be legally required in connection with such
registration.

     Each such Stockholder agrees that, upon receipt of any notice from the
Company of the happening of any event of the kind described in Section 5.04(e),
such Stockholder will forthwith discontinue disposition of Registrable
Securities pursuant to the registration statement covering such Registrable
Securities until such Stockholder's receipt of the copies of the supplemented or
amended prospectus contemplated by Section 5.04(e), and, if so directed by the
Company, such Stockholder will deliver to the Company all copies, other than any
permanent file copies then in such Stockholder's possession, of the most recent
prospectus covering such Registrable Securities at the time of receipt of such
notice. In the event that the Company shall give such notice, the Company shall
extend the period during which such registration statement shall be maintained
effective (including the period referred to in Section 5.04(a)) by the number of
days during the period from and including the date of the giving of notice
pursuant to Section 5.04(e) to the date when the Company shall make available to
such Stockholder a prospectus supplemented or amended to conform with the
requirements of Section 5.04(e).

     SECTION 5.05. INDEMNIFICATION BY THE COMPANY. The Company agrees to
indemnify and hold harmless each Stockholder holding Registrable Securities
covered by a registration statement, its officers, directors and agents, and
each person, if any, who controls such Stockholder within the meaning of Section
15 of the Securities Act or Section 20 of the Exchange Act from and against any
and all losses, claims, damages and liabilities caused by any untrue statement
or alleged untrue statement of a material fact contained in any registration
statement or prospectus relating to the Registrable Securities (as amended or
supplemented if the Company shall have furnished any amendments or supplements
thereto) or any preliminary prospectus, or caused by any omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, except insofar as such
losses, claims, damages or liabilities are caused by any such untrue statement
or omission or alleged untrue statement or omission based upon information
furnished in writing to the Company by such Stockholder or on such Stockholder's
behalf expressly for use therein; PROVIDED that with respect to any untrue
statement or omission or alleged untrue statement or omission made in any
preliminary prospectus, or in any prospectus, as the case may be, the indemnity
agreement contained in this paragraph shall not apply to the extent that any
such loss, claim, damage, liability or expense results from the fact that a
current copy of the prospectus (or, in the case of a prospectus, the prospectus
as amended or supplemented) was not sent or given to the person asserting any
such loss, claim, damage, liability or expense at or prior to the written
confirmation of the sale of the Registrable Securities


                                       24
<PAGE>

concerned to such person if it is determined that the Company has provided such
prospectus and it was the responsibility of such Stockholder to provide such
person with a current copy of the prospectus (or such amended or supplemented
prospectus, as the case may be) and such current copy of the prospectus (or such
amended or supplemented prospectus, as the case may be) would have cured the
defect giving rise to such loss, claim, damage, liability or expense. The
Company also agrees to indemnify any underwriters of the Registrable Securities,
their officers and directors and each person who controls such underwriters on
substantially the same basis as that of the indemnification of the Stockholders
provided in this Section 5.05.

     SECTION 5.06. INDEMNIFICATION BY PARTICIPATING STOCKHOLDERS. Each
Stockholder holding Registrable Securities included in any registration
statement agrees, severally but not jointly, to indemnify and hold harmless the
Company, its officers, directors and agents and each person, if any, who
controls the Company within the meaning of either Section 15 of the Securities
Act or Section 20 of the Exchange Act to the same extent as the foregoing
indemnity from the Company to such Stockholder, but only (i) with respect to
information furnished in writing by such Stockholder or on such Stockholder's
behalf expressly for use in any registration statement or prospectus relating to
the Registrable Securities, or any amendment or supplement thereto, or any
preliminary prospectus or (ii) to the extent that any loss, claim, damage,
liability or expense described in Section 5.05 results from the fact that a
current copy of the prospectus (or, in the case of a prospectus, the prospectus
as amended or supplemented) was not sent or given to the person asserting any
such loss, claim, damage, liability or expense at or prior to the written
confirmation of the sale of the Registrable Securities concerned to such person
if it is determined that it was the responsibility of such Stockholder to
provide such person with a current copy of the prospectus (or such amended or
supplemented prospectus, as the case may be) and such current copy of the
prospectus (or such amended or supplemented prospectus, as the case may be)
would have cured the defect giving rise to such loss, claim, damage, liability
or expense. Each such Stockholder also agrees to indemnify and hold harmless
underwriters of the Registrable Securities, their officers and directors and
each person who controls such underwriters on substantially the same basis as
that of the indemnification of the Company provided in this Section 5.06. As a
condition to including Registrable Securities in any registration statement
filed in accordance with Article 5 hereof, the Company may require that it shall
have received an undertaking reasonably satisfactory to it from any underwriter
to indemnify and hold it harmless to the extent customarily provided by
underwriters with respect to similar securities.

     SECTION 5.07. CONDUCT OF INDEMNIFICATION PROCEEDINGS. In case any
proceeding (including any governmental investigation) shall be instituted


                                       25
<PAGE>

involving any person in respect of which indemnity may be sought pursuant to
this Article 5, such person (an "INDEMNIFIED PARTY") shall promptly notify the
person against whom such indemnity may be sought (the "INDEMNIFYING PARTY") in
writing and the Indemnifying Party shall assume the defense thereof, including
the employment of counsel reasonably satisfactory to such Indemnified Party, and
shall assume the payment of all fees and expenses; PROVIDED that the failure of
any Indemnified Party so to notify the Indemnifying Party shall not relieve the
Indemnifying Party of its obligations hereunder except to the extent that the
Indemnifying Party is materially prejudiced by such failure to notify. In any
such proceeding, any Indemnified Party shall have the right to retain its own
counsel, but the fees and expenses of such counsel shall be at the expense of
such Indemnified Party unless (i) the Indemnifying Party and the Indemnified
Party shall have mutually agreed to the retention of such counsel or (ii) in the
reasonable judgment of such Indemnified Party representation of both parties by
the same counsel would be inappropriate due to actual or potential differing
interests between them. It is understood that the Indemnifying Party shall not,
in connection with any proceeding or related proceedings in the same
jurisdiction, be liable for the reasonable fees and expenses of more than one
separate firm of attorneys (in addition to any local counsel) at any time for
all such Indemnified Parties, and that all such fees and expenses shall be
reimbursed as they are incurred. In the case of any such separate firm for the
Indemnified Parties, such firm shall be designated in writing by the Indemnified
Parties. The Indemnifying Party shall not be liable for any settlement of any
proceeding effected without its written consent, but if settled with such
consent, or if there be a final judgment for the plaintiff, the Indemnifying
Party shall indemnify and hold harmless such Indemnified Parties from and
against any loss or liability (to the extent stated above) by reason of such
settlement or judgment. No Indemnifying Party shall, without the prior written
consent of the Indemnified Party, effect any settlement of any pending or
threatened proceeding in respect of which any Indemnified Party is or could have
been a party and indemnity could have been sought hereunder by such Indemnified
Party, unless such settlement includes an unconditional release of such
Indemnified Party from all liability arising out of such proceeding.

     SECTION 5.08. CONTRIBUTION. If the indemnification provided for in this
Article 5 is unavailable to the Indemnified Parties in respect of any losses,
claims, damages or liabilities referred to herein, then each such Indemnifying
Party, in lieu of indemnifying such Indemnified Party, shall contribute to the
amount paid or payable by such Indemnified Party as a result of such losses,
claims, damages or liabilities (i) as between the Company and the Stockholders
holding Registrable Securities covered by a registration statement on the one
hand and the underwriters on the other, in such proportion as is appropriate to
reflect the relative benefits received by the Company and such Stockholders on
the one hand


                                       26
<PAGE>

and the underwriters on the other, from the offering of the Registrable
Securities, or if such allocation is not permitted by applicable law, in such
proportion as is appropriate to reflect not only the relative benefits but also
the relative fault of the Company and such Stockholders on the one hand and of
such underwriters on the other in connection with the statements or omissions
which resulted in such losses, claims, damages or liabilities, as well as any
other relevant equitable considerations and (ii) as between the Company on the
one hand and each such Stockholder on the other, in such proportion as is
appropriate to reflect the relative fault of the Company and of each such
Stockholder in connection with such statements or omissions, as well as any
other relevant equitable considerations. The relative benefits received by the
Company and such Stockholders on the one hand and such underwriters on the other
shall be deemed to be in the same proportion as the total proceeds from the
offering (net of underwriting discounts and commissions but before deducting
expenses) received by the Company and such Stockholders bear to the total
underwriting discounts and commissions received by such underwriters, in each
case as set forth in the table on the cover page of the prospectus. The relative
fault of the Company and such Stockholders on the one hand and of such
underwriters on the other shall be determined by reference to, among other
things, whether the untrue or alleged untrue statement of a material fact or the
omission or alleged omission to state a material fact relates to information
supplied by the Company and such Stockholders or by such underwriters. The
relative fault of the Company on the one hand and of each such Stockholder on
the other shall be determined by reference to, among other things, whether the
untrue or alleged untrue statement of a material fact or the omission or alleged
omission to state a material fact relates to information supplied by such party,
and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission.

     The Company and the Stockholders agree that it would not be just and
equitable if contribution pursuant to this Section 5.08 were determined by pro
rata allocation (even if the underwriters were treated as one entity for such
purpose) or by any other method of allocation which does not take account of the
equitable considerations referred to in the immediately preceding paragraph. The
amount paid or payable by an Indemnified Party as a result of the losses,
claims, damages or liabilities referred to in the immediately preceding
paragraph shall be deemed to include, subject to the limitations set forth
above, any legal or other expenses reasonably incurred by such Indemnified Party
in connection with investigating or defending any such action or claim.
Notwithstanding the provisions of this Section 5.08, no underwriter shall be
required to contribute any amount in excess of the amount by which the total
price at which the Registrable Securities underwritten by it and distributed to
the public were offered to the public exceeds the amount of any damages which
such underwriter has otherwise been required to pay by reason of such untrue or
alleged untrue statement or omission or alleged


                                       27
<PAGE>

omission, and no Stockholder shall be required to contribute any amount in
excess of the amount by which the total price at which the Registrable
Securities of such Stockholder were offered to the public exceeds the amount of
any damages which such Stockholder has otherwise been required to pay by reason
of such untrue or alleged untrue statement or omission or alleged omission. No
person guilty of fraudulent misrepresentation (within the meaning of Section
11(f) of the Securities Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation. Each such Stockholder's
obligation to contribute pursuant to this Section 5.08 is several in the
proportion that the proceeds of the offering received by such Stockholder bears
to the total proceeds of the offering received by all such Stockholders and not
joint.

     SECTION 5.09. PARTICIPATION IN PUBLIC OFFERING. No Person may participate
in any Public Offering hereunder unless such Person (a) agrees to sell such
Person's securities on the basis provided in any underwriting arrangements
approved by the Persons entitled hereunder to approve such arrangements, and (b)
completes and executes all questionnaires, powers of attorney, indemnities,
underwriting agreements and other documents reasonably and customarily required
under the terms of such underwriting arrangements and the provisions of this
Agreement in respect of registration rights.

     SECTION 5.10. OTHER INDEMNIFICATION. Indemnification similar to that
specified herein (with appropriate modifications) shall be given by the Company
and each Stockholder participating therein with respect to any required
registration or other qualification of securities under any federal or state law
or regulation or governmental authority other than the Securities Act.

     SECTION 5.11. COOPERATION BY THE COMPANY. In the event any Stockholder
shall transfer any Registrable Securities pursuant to Rule 144A under the
Securities Act, the Company shall cooperate with such Stockholder (which shall
include, without limitation, making registration rights with respect to the
Registrable Securities to be sold (or securities issuable or to be issued in
exchange therefor) available to the ultimate purchasers thereof) and shall
provide to such Stockholder such information as such Stockholder shall
reasonably request, PROVIDED that any registration rights made available
pursuant hereto shall not be on terms substantially more favorable to the
possessors thereof than the registration rights granted herein to the DLJMB
Entities.


                                       28
<PAGE>

                                    ARTICLE 6
                                  MISCELLANEOUS

     SECTION 6.01. ENTIRE AGREEMENT; EFFECTIVENESS. (a) This Agreement
constitutes the entire agreement among the parties hereto and supersedes all
prior agreements and understandings, oral and written, among the parties hereto
with respect to the subject matter hereof, including without limitation the
Original Agreement.

     (b) This Amended and Restated Agreement shall be effective upon
consummation of the Exchange. In the event that the Exchange is consummated but
the Initial Public Offering and the Distribution are not consummated within 10
Business Days thereafter, each party hereto agrees to execute an amendment to
this Agreement with such revisions hereto as are appropriate to reflect the fact
that such transactions shall not have been effected, including without
limitation the addition of Sections 3.06(b), 4.01 and 6.04 of the Original
Agreement.

     SECTION 6.02. BINDING EFFECT; BENEFIT; ACTION BY DLJMB ENTITIES; WAIVER.
(a) This Agreement shall inure to the benefit of and be binding upon the parties
hereto and their respective heirs, successors, legal representatives and
permitted assigns. Nothing in this Agreement, expressed or implied, shall confer
on any Person other than the parties hereto, their respective heirs, successors,
legal representatives and permitted assigns, the DLJ Entities, and DLJ Merchant
Banking II, Inc., any rights, remedies, obligations or liabilities under or by
reason of this Agreement.

     (b) Any right or action that may be taken at the election of the DLJMB
Entities may be taken at the election of the holders of a majority of the Shares
then held by the DLJMB Entities and their Permitted Transferees.

     (c) The parties hereto who were parties to the Original Agreement hereby
acknowledge that Section 4.01 of the Original Agreement shall not apply to the
Exchange and waive any rights that may have arisen under such Section as a
result of the transfer of Shares by the LLC to the Company pursuant to the
Reorganization.

     SECTION 6.03. EXCLUSIVE FINANCIAL AND INVESTMENT BANKING ADVISOR. During
the period from and including the date hereof through and including the fifth
anniversary of the date hereof, Donaldson, Lufkin & Jenrette Securities
Corporation ("DLJSC"), or any Affiliate of DLJSC that the DLJMB Entities may
choose in their sole discretion, shall be engaged as the exclusive financial and
investment banking advisor of the Company.



                                       29
<PAGE>

     SECTION 6.04. PRE-EMPTIVE RIGHTS. (a) If the Company proposes to issue any
Company Securities (other than (i) to employees of the Company or any subsidiary
pursuant to employee benefit plans or arrangements approved by the Board
(including upon the exercise of employee stock options), (ii) in connection with
any bona fide, arm's length direct or indirect merger, acquisition or similar
transaction, (iii) pursuant to a Public Offering, (iv) upon the exercise of
Warrants or High Yield Warrants, or (v) on or prior to the Closing Date), each
Other Stockholder shall have the pre-emptive right to acquire its pre-emptive
portion of such Company Securities, at the same price per Company Security at
which such Company Securities are sold in such issuance. For these purposes,
"PRE-EMPTIVE PORTION" shall mean a fraction, the numerator of which is the
Initial Ownership of such Stockholder and the denominator of which is the
Initial Ownership of all Stockholders.

     (b) The Company shall provide written notice to each Other Stockholder at
least twenty days prior to any issuance of Company Securities with respect to
which such Other Stockholder would have pre-emptive rights pursuant to clause
(a) above. Each Other Stockholder shall then have ten days from its receipt of
such notice in which to provide written notice to the Company of its exercise of
its rights pursuant to this Section 6.04.

     (c) The rights of any Other Stockholder under this Section 6.04 shall
expire at such time as such Other Stockholder owns less than 40% of its Initial
Ownership of Common Stock.

     (d) The Company shall not be under any obligation to consummate any
proposed issuance of Company Securities, regardless of whether it shall have
delivered a written notice in respect of such issuance.

     SECTION 6.05. ASSIGNABILITY. This Agreement shall not be assignable by any
party hereto, except that any Person acquiring Shares who is required by the
terms of this Agreement or any employment agreement or stock purchase, option,
stock option or other compensation plan of the Company or any Subsidiary to
become a party hereto shall (unless already bound hereby) execute and deliver to
the Company an agreement to be bound by this Agreement and shall thenceforth be
a "STOCKHOLDER". Any Stockholder who ceases to own beneficially any Shares shall
cease to be bound by the terms hereof (other than the provisions of Sections
5.05, 5.06, 5.07, 5.08, and 5.10 applicable to such Stockholder with respect to
any offering of Registrable Securities completed before the date such
Stockholder ceased to own any Shares).

     SECTION 6.06. AMENDMENT; WAIVER; TERMINATION. No provision of this
Agreement may be waived except by an instrument in writing executed by the


                                       30
<PAGE>

party against whom the waiver is to be effective. No provision of this Agreement
may be amended or otherwise modified except by an instrument in writing executed
by (i) the Company with the approval of the Board, (ii) DLJ Merchant Banking II,
Inc., and (iii) CRL, until such time as CRL is no longer entitled to nominate a
director to the Board; PROVIDED that if any such amendment or modification has
an adverse effect on any Stockholder that is materially disproportionate to the
effect of such amendment or modification on Stockholders generally, the approval
of such Stockholder shall also be required.

     SECTION 6.07. NOTICES. All notices, requests and other communications to
any party hereunder shall be in writing (including facsimile transmissions and
shall be given,

         if to the Company or the Management Stockholders, to:

                  Charles River Laboratories International, Inc.
                  251 Ballardvale Street
                  Wilmington, MA 01887
                  Attention: Dennis R. Shaughnessy
                  Fax: (978) 988-5665

and a copy to the DLJMB Entities at their address listed below;

         if to any or all of the DLJMB Entities, to:

                  DLJ Merchant Banking Partners II, L.P.
                  277 Park Avenue
                  New York, New York 10172
                  Attention: Thompson Dean
                  Fax:  (212) 892-7272

         with a copy to:

                  Davis Polk & Wardwell
                  450 Lexington Avenue
                  New York, New York  10017
                  Attention:  George R. Bason, Jr.
                  Fax:  (212) 450-4800


                                       31
<PAGE>

         if to CRL, to:

                  B&L CRL, Inc.
                  c/o Bausch & Lomb Incorporated
                  One Bausch & Lomb Place
                  Rochester, NY 14604
                  Attention: Alan Farnsworth
                  Fax: 716-338-8017

         with a copy to:

                  Nixon Peabody LLP
                  Clinton Square
                  Rochester, NY 14603
                  Attention: Deborah McLean Quinn
                  Fax: (716) 263-1600

         if to DLJ Investment Partners, L.P., to:

                  DLJ Investment Partners, L.P.
                  277 Park Avenue
                  New York, NY 10172
                  Attention: Ivy Dodes
                  Fax: 212-892-7272

         if to DLJ Investment Funding, Inc.,  to:

                  DLJ Investment Funding, Inc.
                  277 Park Avenue
                  New York, NY 10172
                  Attention: John Moriarty
                  Fax: 212-892-7555

         if to DLJ ESC II, L.P., to:

                  DLJ ESC II L.P.
                  c/o DLJ LBO Plans
                  Management Corporation
                  277 Park Avenue
                  New York, NY 10172
                  Attention: John Moriarty
                  Fax: 212-892-7555


                                       32
<PAGE>

         if to BB, to:

                  Brown Brothers Harriman & Co.
                  59 Wall Street
                  New York, NY 10005
                  Attention: Joseph P. Donlan
                  Fax: 212-493-8429

         with a copy to:

                  Paul Weiss Rifkind Wharton & Garrison
                  1285 Avenue of the Americas
                  New York, NY 10019-6064
                  Attention: Marilyn Sobel
                  Fax: 212-757-3990

         if to Carlyle, to:

                  Carlyle Group L.P.
                  520 Madison Avenue
                  41st Floor
                  New York, NY 10022
                  Attention: Mr. Mark Alter
                  Fax: 212-381-4950

         if to the TCW Entities, to:

                  Trust Company of the West
                  11100 Santa Monica Blvd.
                  Suite 2000
                  Los Angeles, CA 90025
                  Attention: Mr. Jim Shevlet
                  Fax: 310-235-5967

         if to Steven Chubb, to:

                  Matritech
                  330 Nevada Street
                  Newton, MA 02160
                  Fax: 617-928-0821

         if to William Waltrip, to:


                                       33
<PAGE>

                  1261 Pequot Avenue
                  Southport, CT 06490
                  Fax:

     All notices, requests and other communications shall be deemed received on
the date of receipt by the recipient thereof if received prior to 5 p.m. in the
place of receipt and such day is a business day in the place of receipt.
Otherwise, any such notice, request or communication shall be deemed not to have
been received until the next succeeding business day in the place of receipt.
Any notice, request or other written communication sent by facsimile
transmission shall be confirmed by certified mail, return receipt requested,
posted within one Business Day, or by personal delivery, whether courier or
otherwise, made within two Business Days after the date of such facsimile
transmission.

     Any Person who becomes a Stockholder shall provide its address and fax
number to the Company, which shall promptly provide such information to each
other Stockholder.

     SECTION 6.08. HEADINGS. The headings contained in this Agreement are for
convenience only and shall not affect the meaning or interpretation of this
Agreement.

     SECTION 6.09. COUNTERPARTS. This Agreement may be executed in any number of
counterparts, each of which shall be deemed to be an original and all of which
together shall be deemed to be one and the same instrument.

     SECTION 6.10. APPLICABLE LAW. THIS AGREEMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF DELAWARE WITHOUT REGARD
TO THE CONFLICTS OF LAW RULES OF SUCH STATE.

     SECTION 6.11. SPECIFIC ENFORCEMENT. Each party hereto acknowledges that the
remedies at law of the other parties for a breach or threatened breach of this
Agreement would be inadequate and, in recognition of this fact, any party to
this Agreement, without posting any bond, and in addition to all other remedies
which may be available, shall be entitled to obtain equitable relief in the form
of specific performance, a temporary restraining order, a temporary or permanent
injunction or any other equitable remedy which may then be available.

     SECTION 6.12. CONSENT TO JURISDICTION. Any suit, action or proceeding
seeking to enforce any provision of, or based on any matter arising out of or in
connection with, this Agreement or the transactions contemplated hereby may be
brought in the United States District Court for the Southern District of New
York


                                       34
<PAGE>

or any other New York State court sitting in New York City, and each of the
parties hereby consents to the non-exclusive jurisdiction of such courts (and of
the appropriate appellate courts therefrom) in any such suit, action or
proceeding and irrevocably waives, to the fullest extent permitted by law, any
objection which it may now or hereafter have to the laying of the venue of any
such suit, action or proceeding in any such court or that any such suit, action
or proceeding which is brought in any such court has been brought in an
inconvenient forum. Process in any such suit, action or proceeding may be served
on any party anywhere in the world, whether within or without the jurisdiction
of any such court. Without limiting the foregoing, each party agrees that
service of process on such party as provided in Section 6.07 shall be deemed
effective service of process on such party.


                                       35
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Amended and
Restated Agreement to be duly executed as of the day and year first above
written.

                           CHARLES RIVER LABORATORIES
                           INTERNATIONAL, INC.

                              /s/ Charles River Laboratories, Inc.
                              -------------------------------------

                           CRL ACQUISITION LLC

                              /s/ CRL Acquisition LLC
                              -------------------------------------

                           B&L CRL, INC.

                              /s/ B&L CRL, Inc.
                              -------------------------------------

                           DLJ MERCHANT BANKING
                           PARTNERS II, L.P.


                           By:DLJ MERCHANT BANKING II, INC.
                              Managing General Partner

                              /s/ DLJ Merchant Banking II, INC.
                              -------------------------------------




                                       36
<PAGE>

                           DLJ MERCHANT BANKING
                           PARTNERS II-A, L.P.

                           BY  DLJ MERCHANT BANKING II, INC.,
                               Managing General Partner

                              /s/ DLJ Merchant Banking II, INC.
                              -------------------------------------

                           DLJ OFFSHORE PARTNERS II, C.V.

                           By: DLJ OFFSHORE MANAGEMENT N.V.,
                               Managing General Partner


                              /s/ DLJ Offshore Management, N.V.
                              -------------------------------------


                           DLJ DIVERSIFIED PARTNERS, L.P.

                           BY DLJ DIVERSIFIED PARTNERS, INC.,
                              Managing General Partner


                              /s/ DLJ Diversified Partners, Inc.
                              -------------------------------------

                           DLJ DIVERSIFIED PARTNERS-A, L.P.

                           BY DLJ DIVERSIFIED PARTNERS, INC.,
                              Managing General Partner

                              /s/ DLJ Diversified Partners, Inc.,
                              ------------------------------------



                                       37
<PAGE>

                           DLJMB FUNDING II, INC.

                              /s/ DLJMB Funding II, Inc.
                              ---------------------------------------

                           DLJ MILLENNIUM PARTNERS, L.P.

                           By:      DLJ MERCHANT BANKING II, INC.,
                                    Managing General Partner

                              /s/ DLJ Merchant Banking II, Inc.
                              ---------------------------------------

                           DLJ MILLENNIUM PARTNERS-A, L.P.

                           By:      DLJ MERCHANT BANKING II, INC.,
                                    Managing General Partner

                              /s/ DLJ Merchant Banking II, Inc.
                              ---------------------------------------

                           DLJ EAB PARTNERS , L.P.
                           By:      DLJ LBO PLANS MANAGEMENT
                                    CORPORATION,
                                    Managing General Partner

                              /s/ DLJ LBO Plans Management Corporation
                              -----------------------------------------



                                       38
<PAGE>

                           DLJ FIRST ESC, L.P.

                           By: DLJ LBO PLANS MANAGEMENT
                               CORPORATION,
                               Managing General Partner

                              /s/ DLJ LBO Plans Management Corporation
                              -----------------------------------------

                           SPROUT CAPITAL VIII, L.P.

                           By: DLJ CAPITAL CORP.
                               Managing General Partner

                              /s/ DLJ Capital Corp.
                              --------------------------------------

                           SPROUT VENTURE CAPITAL, L.P.

                           By: DLJ CAPITAL CORP.
                               Managing General Partner

                              /s/ DLJ Capital Corp.
                              --------------------------------------

                           DLJ CAPITAL CORP.

                              /s/ DLJ Capital Corp.
                              --------------------------------------




                                       39
<PAGE>

                           DLJ INVESTMENT PARTNERS, L.P.

                           By: DLJ INVESTMENT PARTNERS, INC.,
                               Managing General Partner

                              /s/ DLJ Investment Partners, Inc.
                              -------------------------------------

                           DLJ ESC II L.P.

                           By: DLJ LBO PLANS MANAGEMENT
                               CORPORATION,
                               General Partner

                              /s/ DLJ LBO Plans Management Corporation
                              ----------------------------------------

                           DLJ INVESTMENT FUNDING, INC.

                              /s/ DLJ Investment Funding, Inc.
                              -------------------------------------

                           THE 1818 MEZZANINE FUND, L.P.

                           By: BROWN BROTHERS HARRIMAN & CO.
                               General Partner

                              /s/ Brown Brothers Harriman & Co.
                              -------------------------------------



                                       40
<PAGE>

                           CARLYLE HIGH YIELD PARTNERS, L.P.

                           By: TCG High Yield, L.L.C.
                               General Partner

                              /s/ TCG High Yield, L.L.C.
                              --------------------------------------


                           MANAGEMENT STOCKHOLDERS

                           /s/ James C. Foster
                           ---------------------------------
                           James C. Foster

                           /s/ Henry L. Foster
                           ---------------------------------
                           Henry L. Foster

                           /s/ Thomas F. Ackerman
                           ---------------------------------
                           Thomas F. Ackerman

                           /s/ Dennis R. Shaughnessy
                           ---------------------------------
                           Dennis R. Shaughnessy

                           /s/ Julia D. Palm
                           ---------------------------------
                           Julia D. Palm

                           /s/ Real H. Renaud
                           ---------------------------------
                           Real H. Renaud

                           /s/ Gilbert M. Slater
                           ---------------------------------
                           Gilbert M. Slater

                           /s/ David P. Johst
                           ---------------------------------
                           David P. Johst




                                       41
<PAGE>


                           /s/ Dr. Charn Sun Lee
                           ---------------------------------
                           Dr. Charn Sun Lee

                           /s/ Dr. Jorg M. Geller
                           ---------------------------------
                           Dr. Jorg M. Geller

                           /s/ Dr. Christophe Berthoux
                           ---------------------------------
                           Dr. Christophe Berthoux

                           /s/ Dr. Raj Bhalla
                           ---------------------------------
                           Dr. Raj Bhalla

                           /s/ Toshihide Kashiwagi
                           ---------------------------------
                           Toshihide Kashiwagi


                                       42
<PAGE>

                  TCW/CRESCENT MEZZANINE PARTNERS II, L.P.

                  By: TCW/Crescent Mezzanine II, L.P.
                      its general partner or managing owner

                  By: TCW/Crescent Mezzanine, L.L.C.
                      its general partner

                      /s/ TCW/Crescent Mezzanine, L.L.C.
                      --------------------------------------

                  TCW/CRESCENT MEZZANINE TRUST II

                  By: TCW/Crescent Mezzanine II, L.P.
                      its general partner or managing owner

                  By: TCW/Crescent Mezzanine, L.L.C.
                      its general partner

                      /s/ TCW/Crescent Mezzanine, L.L.C.
                      --------------------------------------

                  CRESCENT/MACH I PARTNERS, L.P.

                  By: TCW Asset Management Company,
                      as Portfolio Manager and as
                      Attorney-in-Fact for the Partnership

                  By: /s/ TCW Asset Management Company
                      --------------------------------------


                                       43
<PAGE>

                  TCW LEVERAGED INCOME TRUST, L.P.

                  By: TCW Investment Management Company,
                      as Investment Advisor

                      /s/ TCW Investment Management Company
                      --------------------------------------

                  By: TCW Advisors (Bermuda), Ltd., as general partner

                      /s/ TCW Advisors, Ltd.
                      --------------------------------------

                  TCW LEVERAGED INCOME TRUST II, L.P.

                  By: TCW Investment Management Company,
                      as Investment Advisor

                      /s/ TCW Investment Management Company
                      --------------------------------------

                  By: TCW (LINC II), L.P., as general partner

                  By: TCW Advisors (Bermuda), Ltd., as its
                      general partner

                      /s/ TCW Advisors, Ltd.
                      --------------------------------------



                                       44
<PAGE>

                  /s/ Stephen Chubb
                  ---------------------------------
                  Stephen Chubb

                  /s/ William Waltrip
                  ---------------------------------
                  William Waltrip


                                       45