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                                                                    EXHIBIT 10.1

     ***PORTIONS OF THIS EXHIBIT MARKED BY BRACKETS ("[_____]") OR OTHERWISE
  INDICATED HAVE BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT.
       THE OMITTED PORTIONS HAVE BEEN FILED SEPARATELY WITH THE SECURITIES
                           AND EXCHANGE COMMISSION.***

           AGREEMENT FOR PURCHASE OF EQUIPMENT, REAGENTS AND SUPPLIES

THIS AGREEMENT, (the "Agreement"), is effective this first day of May , 2003
("Effective Date "), by and between Quest Diagnostics Incorporated, a Delaware
corporation, with an address at One Malcolm Avenue, Teterboro, NJ 07608 ("Quest
Diagnostics") and Cytyc Corporation, a Delaware corporation with offices at 85
Swanson Road, Boxborough, MA 01719 ("Seller" or "Cytyc").

WHEREAS, Quest Diagnostics intends to purchase or lease certain equipment and
purchase reagents and supplies (collectively, and including all components
thereof, "Products") from Seller;

WHEREAS, Cytyc is the manufacturer and distributor of a cervical sample
preparation system known as the ThinPrep(R)Pap Test (the "Test") for liquid
based thin-layer cervical sample preparation which includes certain instruments
and disposables consisting of one vial and one collection device ("Physician
Kit") and one filter and one slide ("Lab Kit")(collectively "Full Kits"); and

WHEREAS, the parties desire to set forth the terms and conditions pursuant to
which such purchase transactions shall be made.

NOW THEREFORE, in consideration of the mutual covenants contained herein, and
intending to be legally bound hereby, Quest Diagnostics and Seller hereby agree
as follows:

1.0  DIAGNOSTIC EQUIPMENT

1.1  Purchase and Lease
     Quest Diagnostics intends to purchase or lease, and Seller intends to sell
     or lease to Quest Diagnostics, the equipment ("Equipment") listed in
     Exhibit 1.1, attached hereto and incorporated by reference.

1.2  Software and License.
     The Equipment includes proprietary software and documentation owned by
     Seller ("Seller Software"), which is hereby licensed to Quest Diagnostics
     under a non-exclusive, non-transferable license solely for Quest
     Diagnostics' own use in connection with the use of Equipment, Reagents or
     Supplies supplied by Seller. Quest Diagnostics may not copy or modify in
     whole or in part the Seller Software owned by Seller nor make it available
     in any form to any third party. If Quest Diagnostics is a unit or agency of
     the U.S. Government or a contractor which will or may supply any Seller
     Software to a unit or agency of the U.S. Government, Quest Diagnostics
     agrees that any software included with or in the Equipment represents
     "Commercial Computer Software," that the government's use of such software
     is subject to "Restricted Rights" and that before such software is
     transferred, it shall be marked with the required restricted rights
     legend(s) as provided in the Department of Defense Federal Acquisition
     Regulations 52.227-7013 or corresponding government regulations. The term
     of the license(s) extends from the date of this Agreement and shall
     continue in perpetuity unless Quest Diagnostics breaches and fails to cure
     within thirty (30) days of notice thereof any material term of this
     Agreement, at which time Seller may revoke the license(s).

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1.3  Installation
     Seller's qualified technicians shall install and test the Equipment
     purchased or leased by Quest Diagnostics, in accordance with its then
     current reasonable practice, at no additional cost to Quest Diagnostics.

2.0  REAGENTS and SUPPLIES

2.1  Generally
     Quest Diagnostics intends to purchase, and Seller intends to sell to Quest
     Diagnostics, the reagents ("Reagents") and other supplies ("Supplies")
     listed in Exhibit 2.1, attached hereto and incorporated by reference.

2.2  Reporting
     Quest Diagnostics shall deliver to Cytyc within twenty (20) business days
     following the end of each month during the term, an aggregate report
     detailing the number of Tests performed by Quest Diagnostics during the
     prior month. Seller shall have the right, at its expense and subject to the
     provisions below and confidentiality undertakings reasonably satisfactory
     to Quest Diagnostics, to cause a major independent auditing firm, not doing
     business with either Quest Diagnostics or Seller, to audit and examine
     Quest Diagnostics' billing records for the sole purpose of verifying the
     accuracy of reports provided by Quest Diagnostics pursuant to this Section
     2.2. Such audits shall be conducted no more than twice during each 12 month
     period of this Agreement and only during regular business hours and with
     reasonable prior written notice from Seller to Quest Diagnostics.

2.3  End of Agreement Quarterly Purchasing
     During the last quarter prior to the termination of the Agreement, Quest
     Diagnostics may purchase no more than 110% of the quantity of the Test, Lab
     Kit and Physician Kit purchased during the three months preceding the last
     quarter.

3.0  PRICING
     Quest Diagnostics agrees to pay for and Seller agrees to sell or lease all
     Equipment, Reagents and Supplies at the purchase and rental prices as
     listed in Exhibits 1.1 and 2.1. Such prices shall remain firm during the
     term of this Agreement, subject to any credits to which Quest Diagnostics
     may be entitled pursuant to Exhibit 2.1.

4.0  ORDERS
     When Quest Diagnostics desires to place an order for Equipment, Reagents
     and Supplies, it shall issue a purchase order via fax or electronic data
     interchange (when made available by Seller at its sole option and
     discretion, although Seller agrees to actively explore the development of
     an electronic data interchange that will work with Quest Diagnostics'
     ordering system during the term). All orders shall specify the items and
     quantities ordered, reference a Quest Diagnostics purchase order number and
     shall designate a place for delivery, which terms, together with the terms
     and conditions of this Agreement, shall constitute the entire agreement
     between the parties with respect to the sale or lease of Equipment,
     Reagents and Supplies. Any additional or different terms contained in any
     purchase order, acknowledgment, confirmation, invoice or other document
     shall be null and void.

5.0  DELIVERY
     Seller shall use commercially reasonable efforts to ship Equipment to Quest
     Diagnostics' facilities as promptly as practicable after its receipt of
     purchase order. Seller agrees to ship Reagents and

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     Supplies by the end of the business day following Seller's receipt of a
     purchase order, unless otherwise stated on the purchase order. All
     deliveries shall be made consistent with the purchase order and shall be
     accompanied by a packing slip identifying (i) the items shipped with
     corresponding manufacturer's product number(s), (ii) the quantities
     shipped, and (iii) the Quest Diagnostics' purchase order number.

6.0  SHIPMENTS
     Seller will provide at its expense "no charge" shipping for one purchase
     order designated by Quest Diagnostics as a "no shipping charge" order per
     Quest Diagnostics' facility per calendar month during the term of the
     Agreement. Additional orders shipped per month per Quest Diagnostics'
     facility will be charged the usual and customary shipping charges at
     competitive commercial rates that are actually incurred. Notwithstanding
     the foregoing provision, the Teterboro lab will be permitted two
     "no-charge" purchase order shipments per month.

     Seller shall ship the Equipment, Reagents and Supplies in a manner
     consistent with general industry practice for comparable goods so as to
     minimize deterioration or damage in transit. Shipment will be scheduled
     upon acceptance of Quest Diagnostics' purchase order. Title to all Products
     (except leased Equipment) will pass to Quest Diagnostics free and clear of
     all liens, claims and encumbrances on delivery to carrier at Seller's
     shipping point regardless of any provisions for payments of freight or
     insurance, or selection of carrier by Seller, or of the form of shipping
     documents. Seller is solely liable for the safe arrival of any shipments.

7.0  INSPECTION
     Quest Diagnostics shall have the right to inspect Equipment, Reagents and
     Supplies upon delivery. Within 15 days of the delivery date, Quest
     Diagnostics shall notify Cytyc of any duplicate shipments, over shipments
     or damaged or defective Products and said duplicate or over shipments or
     damaged or defective Products will be returned at no cost to Quest
     Diagnostics. Quest Diagnostics shall submit a return goods authorization
     form to Cytyc and follow the then existing reasonable return procedures of
     Cytyc.

8.0  OWN USE
     Equipment, Reagents and Supplies covered hereunder will be purchased by
     Quest Diagnostics, for Quest Diagnostics' "own use." Quest Diagnostics
     agrees not to resell Equipment, Reagents or Supplies.

9.0  PARTIES BOUND
     For purposes of this Agreement, Quest Diagnostics shall include all direct
     and indirect subsidiaries and affiliates of Quest Diagnostics engaged in
     the laboratory services business in which Quest Diagnostics owns more than
     50% of the equity interest, including Unilab (as defined below) ("Majority
     Owned Subsidiaries"), and all Majority Owned Subsidiaries shall be entitled
     to the benefits of this Agreement, and all Tests utilized by Majority Owned
     Subsidiaries shall be counted in determining whether Quest Diagnostics is
     entitled to a Quarterly Usage Discount pursuant to Exhibit 2.1 attached
     hereto. In addition, all direct and indirect subsidiaries and affiliates of
     Quest Diagnostics engaged in the laboratory services business in which
     Quest Diagnostics, as of the Effective Date, owns more than 29%, and up to
     50% of the equity interest ("Minority Owned Subsidiaries") shall be
     entitled to the pricing and related terms set forth in Section 3 of this
     Agreement, and all Tests utilized by Minority Owned Subsidiaries shall be
     counted in determining whether Quest Diagnostics is entitled to a Quarterly
     Usage Discount pursuant to Exhibit 2.1 attached hereto. Any other
     subsidiary or affiliate of Quest Diagnostics shall have the option to
     become a party to this Agreement upon the giving of a written notice to
     Seller and written acceptance by Seller (such other subsidiaries and
     affiliates, together with

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     Majority Owned Subsidiaries and Minority Owned Subsidiaries being
     collectively referred to as "Participating Subsidiaries"). Upon acceptance
     by Seller, the affiliate or subsidiary agrees to abide by all terms and
     conditions of this Agreement. By signing this Agreement, each party
     acknowledges the termination of the Agreement between Seller and Unilab
     Corporation ("Unilab") dated March 29, 2000 (the "Unilab Agreement"),
     except for the Cooperation and Confidentiality provision contained in the
     Unilab Agreement that survives termination for a period of two years from
     termination. Quest Diagnostics may purchase Equipment, Reagents and
     Supplies pursuant to the terms hereof on behalf of laboratories for which
     it provides management services upon prior written notice and mutual
     written agreement by both Seller and Quest Diagnostics ("Managed
     Laboratories").

10.0 PAYMENT TERMS

10.1 Equipment, Reagents and Supplies
     Seller shall invoice Quest Diagnostics for the Equipment, Reagents and
     Supplies in accordance with the prices set forth in Exhibits 1.1 and 2.1.
     Invoices shall be mailed by Seller to the address set forth for Quest
     Diagnostics on the purchase order and shall reference the Quest
     Diagnostics' purchase order number (or submitted via EDI when applicable).
     Quest Diagnostics will not accept third party invoices. Invoices for
     multiple items shall separately identify the charges for those items.
     Seller understands that its failure to follow these requirements may result
     in delayed payments by Quest Diagnostics. Quest Diagnostics agrees to pay
     all invoices within thirty (30) days of the invoice date, except for all or
     any portion thereof disputed in good faith.

     Quest Diagnostics shall not be obligated to pay that portion of the invoice
     for Equipment, Reagents and/or Supplies that relates to quantities greater
     than those ordered.

10.2 Taxes
     Unless Quest Diagnostics provides Seller with satisfactory proof of
     exemption from taxation, Quest Diagnostics shall pay and be responsible for
     all applicable taxes, whether federal, state, local or otherwise, which may
     be imposed upon the use, possession, ownership, sale or other transfer of
     the Equipment, Reagents and Supplies exclusive of Seller's income and
     related taxes, which shall be paid by Seller. Quest Diagnostics' shall
     reimburse Seller for any such taxes paid by Seller on Quest Diagnostics'
     purchases hereunder.

11.0 NOTICE OF DEFECTS; WARNINGS; RECALLS; WARRANTIES, INDEMNIFICATION AND
     LIMITATION OF LIABILITY
     The parties acknowledge and agree that references to Products and Equipment
     in Sections 11 and 12 of this Agreement shall, in addition to Equipment
     purchased or leased under this Agreement, also be deemed to include the
     Unilab Equipment referenced in Exhibit 1.1A and Quest Diagnostics' existing
     Equipment referenced in Exhibit 12.3.

11.1 Notification: Equipment, Reagents and Supplies' Defects, Warnings or
     Recalls
     In the event any Equipment, Reagents and Supplies do not perform in
     accordance with the Seller's limited warranty package insert and operating
     manuals, Quest Diagnostics shall give notice to Seller of the
     nonconformance.

     Seller will be responsible for promptly notifying Quest Diagnostics of any
     known Product performance problem, or concern regarding Quest Diagnostics'
     purchases, including Product defects, warnings or recalls. Such notice
     shall be communicated in writing in accordance with Section 26 from
     Seller's Quest Diagnostics service representative or other Seller
     representative.

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     Seller shall provide notice to the applicable Quest Diagnostics' sourcing
     manager or other designated Quest contact within two (2) days after Seller
     first becomes aware of any warning or recall or determines that a Product
     contains a material defect, which shall be deemed to include any defects
     that may materially impact any Test result or diagnosis, or any defects
     requiring notice to customers. In connection with any failure to comply
     with the foregoing notice requirement, Quest Diagnostics, in addition to
     other contractual remedies the parties are otherwise entitled to, [_____].

     Seller agrees to cooperate with Quest Diagnostics in discussing corrective
     action plans of Seller and preventative measures to be implemented for the
     future.

11.2 Limited Warranties
     The Products are warranted against defects in workmanship and materials for
     twelve (12) months with respect to Equipment and for twelve (12) months
     with respect to other Products from date of shipment ("Warranty Period").
     In addition, Seller warrants that during the Warranty Period, Products
     shall conform with generally accepted industry standards and perform in
     accordance with all applicable federal and state laws, regulations and
     guidelines (including applicable U.S. Food and Drug Administration
     regulations and guidelines), with published specifications and with any
     additional documentation provided by Seller such as package inserts. Seller
     further warrants that it has good title to all Equipment and that all
     Equipment purchased by Quest Diagnostics will be transferred free and clear
     of all liens, claims and encumbrances. PreservCyt(R) Solution, CytoLyt(R)
     Solution and/or TransCyt(R) Filters shall be shipped a minimum of six (6)
     months prior to their expiration date and shall be replaced at the request
     of Quest Diagnostics if such expiration date expires prior to the end of
     the Warranty Period. Cytyc assumes no liability for Products used after the
     expiration date or Quest Diagnostics' failure to request replacement of
     expired Products within the Warranty Period provided such expiration dates
     are properly reflected on the Product label. Cytyc shall repair or replace
     at its sole expense any defective Product as promptly as is practicable. If
     Seller elects to repair Equipment, and such repair cannot be completed
     within five (5) business days, Seller shall provide Quest Diagnostics with
     loaner Equipment in good working order until such repair can be completed.
     In fulfilling its obligation to provide loaner Equipment for ThinPrep(R)
     3000 Equipment, Seller may provide one ThinPrep 2000 processor and up to a
     maximum of two (2) ThinPrep 2000 Processors if necessary to meet Quest
     Diagnostics' volume requirements in lieu of providing a ThinPrep 3000
     Processor. If the defective Equipment is leased Equipment, and the
     Equipment is not repaired or loaner Equipment provided within five (5)
     business days after the defect arose [_____]. Replacement parts, which may
     be reconditioned, are warranted from the date of installation for the
     remainder of the original Warranty Period, which shall be extended for the
     period commencing from the time the defect arose and continuing during any
     period that Quest Diagnostics is without repaired or replaced Equipment or
     loaner Equipment in good working order. Seller shall be responsible for the
     expense of returning nonconforming Products, and providing conforming
     Products in exchange. [_____] The foregoing warranties shall not apply to
     defects to the extent resulting from Quest Diagnostics' misuse, negligence
     or accident, including, without limitation: operation outside of the
     environmental specifications for the Product; multiple use of a filter, use
     of unauthorized supplies; failure of Quest Diagnostics or any third party
     to perform routine maintenance for which Quest Diagnostics is responsible
     in accordance with operating manuals; installation of software not supplied
     by Cytyc; improper use or connection to incompatible equipment;
     modifications to the Product not authorized by Cytyc; and external causes
     such as, but not limited to, power failure. The foregoing warranties shall
     survive any inspection by Quest Diagnostics. THE FOREGOING PROVISIONS SET
     FORTH CYTYC'S SOLE AND EXCLUSIVE REPRESENTATIONS, WARRANTIES AND
     OBLIGATIONS WITH RESPECT TO THE PRODUCT (S), AND CYTYC MAKES NO OTHER
     WARRANTY OF ANY KIND WHATSOEVER, EXPRESS OR IMPLIED. CYTYC SPECIFICALLY

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     DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
     PARTICULAR PURPOSE, WHETHER ARISING FROM A STATUTE OR OTHERWISE IN LAW,
     EQUITY OR FROM A COURSE OF DEALING OR USAGE OF TRADE. CYTYC'S LIABILITY
     ARISING OUT OF THE MANUFACTURE, SALE OR SUPPLY OF THE PRODUCT(S) OR
     SERVICES OR THEIR USE OR DISPOSITION, WHETHER BASED UPON WARRANTY,
     CONTRACT, TORT OR OTHERWISE, SHALL NOT EXCEED THE ACTUAL PURCHASE PRICE
     PAID BY QUEST DIAGNOSTICS FOR THE PRODUCT(S) OR SERVICES EXCEPT FOR CASES
     IN WHICH REWORK IS REQUIRED OR AS PROVIDED IN CLAUSES 11.3 AND 11.4 BELOW.
     SUCH LIMITED WARRANTY IS GIVEN SOLELY TO QUEST DIAGNOSTICS AND IS NOT GIVEN
     TO, NOR MAY IT BE RELIED UPON BY, ANY THIRD PARTY INCLUDING, WITHOUT
     LIMITATION, CUSTOMERS OF QUEST DIAGNOSTICS. THIS WARRANTY IS VOID UPON
     TRANSFER OF PRODUCT BY QUEST DIAGNOSTICS TO ANY ENTITY.

11.3 Indemnification and Limitation of Liability

     Sections 11.2,11.3 and 11.4 of this Agreement are intended to set out the
     sole basis for Cytyc's liability relating to Products and their use. Cytyc
     agrees to indemnify Quest Diagnostics for certain losses under certain
     conditions, as outlined in Sections 11.3(a) through (c), and 11.4 below.
     Except for wrongful termination of this Agreement by Cytyc (which, when
     used in this paragraph, shall be deemed to mean any termination of this
     Agreement by Cytyc before the expiration of the term of this Agreement or
     any renewal thereof that is not expressly permitted by this Agreement), if
     Sections 11.3(a) - (c) and 11.4 are inapplicable, then Cytyc's liability
     for damages, indemnification or otherwise for any loss, irrespective of how
     or by whom incurred, shall be limited to the Limited Warranty in Section
     11.2 above. Except for wrongful termination of this Agreement by Cytyc and
     for indemnification obligations under this Section 11.3 and Section 11.4,
     in no event shall either party be liable to the other for attorney's fees
     (except as otherwise provided in Sections 11.3(e)(iii) or 11.4 below) or
     any incidental, indirect, special, punitive or consequential damages,
     including lost profits or loss of use. The obligations to indemnify set
     forth in Sections 11.3 and 11.4 constitute the parties' entire obligations
     to indemnify one another.

     (a) The ThinPrep(R) System is intended as a replacement for the
     conventional Pap smear used to screen for cervical cancer or its precursor
     lesions. Determination of slide adequacy and patient diagnosis is at the
     sole discretion of the cytotechnologists and pathologists trained by Cytyc
     to evaluate ThinPrep(R) prepared slides. Cytyc shall indemnify, defend and
     hold harmless Quest Diagnostics and its subsidiaries and affiliates and
     their officers, directors, employees, representatives, successors and
     assigns from and against any and all damages, liabilities, penalties, costs
     or other losses (collectively "Claims") in connection with any third party
     claim, suit, action, demand or proceeding to the extent the Claim arises
     from (i) a Product sold to Quest Diagnostics hereunder that was defective
     in design or contained a manufacturing defect and that such defect caused
     harm to a third party; (ii) a breach of any of representation, warranty or
     covenant of Cytyc contained in this Agreement; or (iii) Cytyc's negligence
     or willful misconduct. Notwithstanding the foregoing, Cytyc shall have no
     obligation to indemnify pursuant to the foregoing provisions to the extent
     any Claim arises out of an act or omission of Quest Diagnostics for which
     Quest Diagnostics is required to indemnify Cytyc pursuant to Section
     11.3(d) below.

     (b) Other than as provided in Section 11.4 below, Section 11.3(a) above
     sets forth Cytyc's sole obligation to indemnify or pay damages or other
     monies and shall only apply if (i) the conditions set out therein strictly
     apply, (ii) the Product has not been resold or leased by Quest Diagnostics,
     and (iii) the Product has not been altered by Quest Diagnostics or any
     third party in any material way and has been used substantially in
     accordance with the then current Product specifications and labeling.

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     (c) For purposes of Section 11.3(a), the terms "defective in design" and
     "manufacturing defect" shall be determined in accordance with the
     provisions of the American Law Institute's Restatement Third, Torts:
     Products Liability (1998).

     (d) Quest Diagnostics shall indemnify, defend and hold harmless Cytyc and
     its subsidiaries and affiliates and their officers, directors, employees,
     representatives, successors and assigns from and against any and all Claims
     in connection with any third party claim, suit, action, demand or
     proceeding to the extent the Claim arises from (i) a breach of any of
     representation, warranty or covenant of Quest Diagnostics contained in this
     Agreement; (ii) or Quest Diagnostics' negligence or willful misconduct.
     Notwithstanding the foregoing, Quest Diagnostics shall have no obligation
     to indemnify pursuant to the foregoing provisions to the extent any Claim
     arises out of an act or omission of Cytyc for which Cytyc is required to
     indemnify Quest Diagnostics pursuant to Section 11.3(a) above.

     (e) With respect to Claims subject to indemnification pursuant to Sections
     11.3(a) and (d) above, the following procedures shall apply:

     Promptly and no later than thirty (30) days after receipt by any entity
     entitled to indemnification under Sections 11.3 (a) or (d) above of notice
     of the commencement or threatened commencement of any civil, criminal,
     administrative, or investigative action or proceeding involving a Claim in
     respect of which the indemnitee will seek indemnification pursuant to any
     such Section, the indemnitee shall notify the indemnitor of such Claim in
     writing. No failure to so notify an indemnitor shall relieve it of its
     obligations under this Agreement except to the extent that it can
     demonstrate damages attributable to such failure. Within fifteen (15) days
     following receipt of written notice from the indemnitee relating to any
     Claim, the indemnitor shall notify the indemnitee in writing if the
     indemnitor elects to assume control of the defense and settlement of that
     Claim (a "Notice of Election"). If the indemnitor delivers a Notice of
     Election relating to any Claim within the required notice period, the
     indemnitor shall be entitled to have sole control over the defense and
     settlement of such Claim and the indemnitee shall provide reasonable non-
     monetary cooperation in defense of such Claim; provided that (A) the
     indemnitee shall be entitled to participate in the defense of such Claim
     and to employ counsel at its own expense to assist in the handling of such
     Claim, and (B) the indemnitor shall obtain the prior written approval, not
     to be unreasonably withheld, of the indemnitee before entering into any
     settlement of such Claim or ceasing to defend against such Claim. After the
     indemnitor has delivered a Notice of Election relating to any Claim in
     accordance with the preceding paragraph, the indemnitor shall not be liable
     to the indemnitee for any legal expenses incurred by the indemnitee in
     connection with the defense of that Claim. In addition, the indemnitor
     shall not be required to indemnify the indemnitee for any amount paid or
     payable by the indemnitee in the settlement of any Claim for which the
     indemnitor has delivered a timely Notice of Election if such amount was
     agreed to without the written consent of the indemnitor. If the indemnitor
     does not deliver a Notice of Election relating to any Claim within the
     required notice period, the indemnitee shall have the right to defend the
     Claim in such manner as it may deem appropriate, at the cost and expense of
     the indemnitor. The indemnitor shall promptly after final adjudication or
     settlement of such Claim, reimburse the indemnitee for all such costs and
     expenses.

11.4 Intellectual Property Indemnity
     (a) If Quest Diagnostics or any of its subsidiaries or affiliates or their
     officers, directors or employees or representatives, successors or assigns
     is sued alleging that a Product or Quest Diagnostics' use thereof or sale
     of results of use infringes a United States patent, trade secret,
     trademark, copyright or other intellectual property right of a third party,
     Cytyc agrees to defend the suit, pay all litigation costs, indemnify Quest
     Diagnostics for any damages awarded or any sums

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     due in connection with any settlement approved by Cytyc, provided Quest
     Diagnostics: gives Cytyc (i) written notice as soon as possible but in no
     event more than 30 days of Quest Diagnostics' receipt of notice of any
     suit; (ii) continuous reasonable non-monetary cooperation in the defense,
     and (iii) complete and sole control over the defense and settlement of any
     such suit. Quest Diagnostics may participate in the defense and settlement
     of any such suit, subject to Cytyc's ultimate right of control. Quest
     Diagnostics shall be solely responsible for attorneys' fees and costs it
     incurs independently of Cytyc's representation, unless Cytyc shall fail to
     defend the suit as required by this Section 11.4(a), in which event Quest
     Diagnostics shall have the right to defend the suit in such manner as it
     may deem appropriate, at the cost and expense of Cytyc. Cytyc shall
     promptly reimburse Quest Diagnostics for all such costs and expenses.

     (b) If Quest Diagnostics is enjoined by a final, unappealable court order,
     or by a settlement approved by Cytyc, from using the Product as sold by
     Cytyc, Cytyc, at its option and in its sole discretion, may (i) procure for
     Quest Diagnostics the right to continue using the Product, (ii) replace or
     modify the Product to avoid infringement, or (iii) repossess the Product in
     exchange for a refund of the depreciated value of the Product. The remedy
     selected by Cytyc shall be Quest Diagnostics' exclusive remedy for any
     damage, cost, or expense resulting from any court order or settlement
     enjoining Quest Diagnostics' use of the Product but the foregoing shall not
     in any way limit Cytyc's indemnification obligations hereunder.

     (c) Notwithstanding any other provision hereof, Cytyc shall have no
     obligation to defend, and shall not be liable for any costs or damages
     awarded, in any suit for infringement concerning (i) any Product made by
     Cytyc according to specifications supplied by Quest Diagnostics, (ii) any
     infringement alleged, based on use by Quest Diagnostics of the Product as
     sold by Cytyc in combination with another item not sold by Cytyc, to the
     extent the alleged infringement arises from the combination or from the
     practice of a method made possible by the combination, (iii) any
     infringement alleged, to the extent based on any Product as modified by or
     used contrary to Product specifications by any party other than Cytyc
     without Cytyc's permission, or (iv) any damage, cost, fee, or expense
     incurred in connection with, or any injunction, sanction, or other order
     resulting from any suit that Cytyc is not given the reasonable opportunity
     to defend.

11.5 Insurance
     Each party shall maintain insurance against such risks (including product
     liability or professional liability, as the case may be) and upon such
     terms (including coverages, deductible limits, and self-insured retentions)
     as is customary for the activities to be conducted by it under this
     Agreement and as appropriate to cover its indemnification obligations under
     this Agreement, provided that the minimum coverage shall be [_____] per
     occurrence and [_____] in the annual aggregate. Such insurance will be
     primary to any other valid and collectible insurance coverage which the
     indemnified party, or any of its parents, subsidiaries, affiliates,
     principals, agents, or assigns, may have or obtain. Each party will furnish
     the other party evidence of such insurance upon request.

11.6 Persistent Performance Issues
     In the event of two (2) consecutive Equipment, Reagents and/or Supplies
     material defects/lot rejections or four (4) Equipment, Reagents and/or
     Supplies material defects/lot rejections in any twelve (12) month period,
     Quest Diagnostics shall have the right to terminate this Agreement.

11.7 Miscellaneous Equipment, Reagents and Supplies Performance Issues
     Seller shall use commercially reasonable efforts to provide at least ninety
     (90) days' advance written notice to Quest Diagnostics of all other issues
     such as product discontinuations, quality control changes, device changes
     and material software upgrades. Quest Diagnostics

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     acknowledges that information disclosed pursuant this Section shall be
     deemed subject to the provisions of the Confidentiality Agreement (as
     defined in Section 18 of this Agreement), and will be used by Quest
     Diagnostics only in furtherance of the purposes of this Agreement).

12.0 TECHNICAL SERVICES; TRAINING; DEVELOPMENT

12.1 Technical Telephone Support
     Seller shall maintain a sufficiently trained and qualified technical
     service force during the term of this Agreement to provide, at no cost to
     Quest Diagnostics, readily available technical support related to the
     Equipment, Reagents and Supplies. Technical support shall include phone
     access to a technical representative of Seller with the following minimum
     telephone support service levels:

     Coverage: 8:30 AM - 5:30PM ( EST ), Monday through Friday, excluding Seller
     designated holidays.

     Response Time: immediate, but in no event later than (one) 1 hour from time
     of initial call.

12.2 Field Service/Technical Support
     Technical support will include help from instrument hardware experts able
     to guide Quest Diagnostics' representatives through part removal and
     replacement procedures.

     If any of the Equipment placed with or purchased by Quest Diagnostics fails
     to perform as specified in the operator's manual and the problem cannot be
     resolved by telephone, then Seller shall dispatch qualified technical
     representative on-site at the designated facility of Quest Diagnostics at
     the expense of Cytyc. A plan for problem resolution shall be provided
     within one (1) business day of the initial call, unless otherwise agreed to
     by Quest Diagnostics.

12.3 Equipment Service
     Equipment Service will be provided by Cytyc Corporation Trained Field
     Service Engineers as described here and detailed in the Service Agreement
     attached hereto as Exhibit 12.3 ("Service Agreement"). Cytyc will service
     all Equipment subject to the Service Agreement [_____]. All new Equipment
     comes with a twelve-month warranty and shall be maintained by Cytyc in
     accordance with the Warranty during the applicable Warranty Period and
     thereafter pursuant to the terms of the Service Agreement at Cytyc's
     expense.

     Quest Diagnostics agrees to perform all required routine operator
     maintenance as listed in the applicable operator's manual. Seller and Quest
     Diagnostics will work together to ensure that all sites perform required
     maintenance.

     Only Seller or Seller-appointed personnel shall service, alter or replace
     the Equipment and/or any accessories during the Warranty Period that are
     necessary to keep the Equipment in good working order.

12.4 Equipment Records
     Within fifteen (15) days after the expiration of each six (6) month period
     during the term of this Agreement, Seller shall provide Quest Diagnostics
     with a report that shall identify all Equipment service calls during the
     preceding six (6) months, so that Quest Diagnostics' best practice team can
     monitor whether mean time between failures (MTBF) for all Equipment is
     within expected time frames. Such reports shall identify each item of
     Equipment serviced and the nature of the repair or failure. If any
     Equipment is found to have a MTBF lower than that which is commercially

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     reasonable and acceptable to the Parties by mutual agreement, Seller's
     field service personnel will be dispatched to service the Equipment
     immediately. All service will be fully documented by Seller and MTBF will
     be monitored each month for six (6) months to ensure that the Equipment
     returns to the expected MTBF.

12.5 Customer Service
     Seller shall maintain a client service department to respond to general
     inquiries related to ordering including order placement status with the
     following minimum service levels:

     Coverage: 8:30 AM to 5:30 PM (EST), Monday to Friday, except Seller-
     designated holidays.

     Response Time: immediate, but in no event later than 1 hour from time of
     initial call.

12.6 Training
     Cytyc to provide, at its expense, training at its headquarters for one
     cytopathologist and one cytotechnologist from each Quest Diagnostics'
     facility that purchases or leases Cytyc Equipment. Additional training of
     Quest Diagnostics' laboratory personnel will be conducted at no additional
     charge to Quest Diagnostics by Cytyc CASs at Quest Diagnostics' facilities
     so long as there are a minimum of four (4) cytotechnologists or
     cytopathologists scheduled for training, otherwise Cytyc will charge Quest
     Diagnostics at its standard rates.

12.7 Development
     Seller and Quest Diagnostics agree to consider specific programs to improve
     the performance of Seller's Equipment, Reagents and Supplies. The parties
     agree to negotiate in good faith an agreement for compensation to Quest
     Diagnostics regarding any mutually agreeable collaboration efforts which
     result in enhancement to the Equipment, Reagents and Supplies or for work
     performed during any evaluations and validations of new Equipment, Reagents
     and Supplies. Quest Diagnostics will not endeavor to begin any development
     programs for which it expects compensation under this Section without the
     express written agreement of Seller. Except as expressly provided in this
     Agreement, nothing herein shall be construed as granting Quest Diagnostics
     a license to any intellectual property or proprietary information of Seller
     except to the limited extent necessary and for the sole purpose of using
     Products purchased under this Agreement and as specifically provided for
     elsewhere in this Agreement.

13.0 TERM AND TERMINATION

13.1 The term of this Agreement shall begin on the Effective Date and terminate
     twenty-four (24) months after the Effective Date, unless sooner terminated
     hereunder.

13.2 Either party may terminate this Agreement if the other party seeks
     protection under the bankruptcy laws (other than as a creditor) or any
     assignment is made for the benefit of creditors or a trustee is appointed
     for all or any portion of such party's assets.

13.3 In the event either party is in breach of any material term, covenant or
     condition of this Agreement, the non-breaching party may terminate the
     Agreement upon thirty (30) days' advance written notice of the breach,
     unless during the thirty (30) day notice period the party in breach cures
     the breach, in which event, the Agreement shall remain in full force and
     effect.

13.4 In addition to other rights of termination set forth in this Agreement,
     commencing on the first day of the thirteenth full calendar month during
     the term of this Agreement, either party may terminate this Agreement for
     any reason at any time on ninety (90) days' advance written notice.

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13.5 The rights and remedies provided hereunder shall be cumulative and be in
     addition to all rights and remedies available to the parties in law and
     equity.

13.6 This Section is in addition to the termination rights available under
     Sections 11.6, 14.4, 14.7 and 23.

14.0 PATIENT CONFIDENTIALITY; PRIVACY; SECURITY REQUIREMENTS
14.1 Definitions
     "HIPAA" means the Health Insurance Portability and Accountability Act of
     1996. "Privacy Regulations" means all of the regulations in effect from
     time to time issued pursuant to HIPAA and applicable to the privacy of
     Individually Identifiable Health Information. "Security Regulations" means
     all of the regulations in effect from time to time issued pursuant to HIPAA
     and applicable to the security of patients' Individually Identifiable
     Health Information. All other terms used, but not otherwise defined in this
     Agreement, shall have the same meaning as those terms defined in the Code
     of Federal Regulations applicable to HIPAA or any successor statute.

14.2 Services Subject to Privacy and Security Laws
     Seller acknowledges that due to the regulated nature of Quest Diagnostics'
     business and operations any services to be provided by Seller that are
     related to the provision of Equipment, Reagents and Supplies under this
     Agreement may be impacted by current and future laws, rules and regulations
     (collectively, "Applicable Laws") regarding collecting, accessing, using,
     disclosing, electronically transmitting, securing, and storing individually
     identifiable health information of patients ("Confidential Information").
     Applicable Laws may include, but shall not be limited to HIPAA, the Privacy
     Regulations, the Security Regulations, other related HIPAA regulations,
     State laws and regulations, and European Union laws and regulations
     regarding data privacy (as applicable).

14.3 Confidentiality and Privacy of Confidential Information
     In the performance of any services that are related to the provision of
     Equipment, Reagents and Supplies under this Agreement, Seller and its
     employees, representatives, or agents may inadvertently obtain or gain
     access to Confidential Information on paper, tape, diskette, CD or other
     tangible media, in instruments or computers, electronically displayed, or
     verbally disclosed. Both Seller and Quest Diagnostics acknowledge that
     Confidential Information is not required for the performance of this
     Agreement. Seller agrees that it shall not use, disclose, or reproduce, in
     any manner, any Confidential Information (including, without limitation,
     laboratory results and patient demographic information) that it obtains or
     to which it gains access as a result of this Agreement. Seller agrees to
     advise all of its employees, representatives or subcontractors acting on
     its behalf of the requirements of this Agreement and to cause each of them
     to become bound to the terms and conditions of this Agreement regarding the
     confidentiality and privacy of Confidential Information. Seller agrees that
     it shall immediately report to Quest Diagnostics any incidents in which it
     or its employees, representatives, or subcontractors gain access to,
     reproduce, use, or disclose Confidential Information.

14.4 Safeguards
     Seller shall adopt, implement and maintain throughout the term of this
     Agreement appropriate and adequate security policies, procedures, and
     practices, physical and technological safeguards, and security mechanisms
     to protect the Confidential Information against unauthorized use,
     disclosure, alteration, or destruction ("Safeguards") and Seller shall
     require its sub-contractors or agents to adopt Safeguards that are equally
     appropriate and adequate. Quest Diagnostics is relying on the
     appropriateness and adequacy of the Safeguards and failure of such

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     Safeguards will constitute a material breach of this Agreement. Quest
     Diagnostics may terminate this Agreement at any time, without penalty, if
     Seller fails to cure any breach of this provision within thirty (30) days
     of notice thereof from Quest Diagnostics.

14.5 Benefit
     This Agreement is not intended to create a third-party beneficiary
     liability and/or to obligate the parties in any way or to create any rights
     to the benefit of any person or entity that is not a party to this
     Agreement, including but not limited to the individuals whose Confidential
     Information will be used and disclosed hereunder.

14.6 Mitigation
     In addition to any rights of indemnification contained in this Agreement,
     Seller will mitigate any harm caused by its breach of this Agreement and/or
     reimburse Quest Diagnostics for the cost of mitigation based upon, arising
     out of or attributable to the acts or omissions of Seller, its employees,
     representatives, officers, directors, agents, or subcontractors for uses or
     disclosures of Confidential Information in violation of this Agreement.

14.7 Amendment
     Seller and Quest Diagnostics agree to amend this Agreement in such manner
     as Quest Diagnostics deems necessary to comply with any amendment of 1)
     HIPAA or other applicable privacy law, 2) the Privacy Regulations, the
     Security Regulations, or other applicable privacy regulations, or 3) any
     applicable court decision, or binding governmental policy or opinion with
     respect to HIPPA, Privacy Regulations or Security Regulations. If the
     parties are unable to agree on an amendment within 30 days of written
     notice from Quest Diagnostics to Seller of the requirement to amend the
     Agreement, Quest Diagnostics may, at its option, terminate this Agreement.

14.8 Interpretation
     Any ambiguity in this Agreement shall be resolved in favor of a meaning
     that permits the parties to comply with all Applicable Laws.

15.0 ASSIGNMENT
     Neither party may assign, or in any way transfer its interest in this
     Agreement without the prior written consent of the other party.
     Notwithstanding the foregoing, either party may assign this Agreement to a
     parent, majority-owned subsidiary, majority owned affiliate or successor
     company (including, but not limited to, by way of merger or other
     acquisition of the assigning party), provided the assigning party (if such
     party survives) remains secondarily liable to the other party under any
     such assignment, without obtaining consent of the other party.

16.0 COMPLIANCE WITH LAWS
     Each of the parties represents and warrants to the other party that it will
     comply with all applicable laws, rules or regulations ("Applicable Laws"),
     including, but not limited to, the federal Physician Self-Referral Law, 42
     U.S.C. 1395nn, and the regulations promulgated thereunder, similar state
     physician self-referral laws and regulation, the federal Medicare/Medicaid
     Anti-kickback Law and regulations promulgated thereunder and similar state
     Anti-kickback laws and regulations, and HIPAA and the HIPAA Privacy
     Regulations, the standard transactions regulations and HIPAA Security
     Regulations (as of the effective dates of those regulations and European
     Union laws or regulations regarding data privacy) as applicable, and as to
     Seller, the federal Food Drug and Cosmetic Act and regulations promulgated
     thereunder. Each party will maintain in full force and effect all necessary
     licenses, permits, and other authorizations required by law to carry out
     its

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     respective duties and obligations under this Agreement. Failure by either
     party to comply with any Applicable Law shall be considered a material
     breach of this Agreement.

17.0 EQUAL EMPLOYMENT OPPORTUNITY/AFFIRMATIVE ACTION To the extent Seller's
     Products or services will be used by Quest Diagnostics in the performance
     of a federal government contract, Seller hereby certifies that all Products
     which are produced, manufactured or, if a service, provided in the United
     States are produced, manufactured or provided in compliance with all
     applicable requirements, orders and regulations of the United States
     Federal Government pertaining to nondiscrimination, equal employment
     opportunity and affirmative action, including, without limitation, the
     following, as the same may be amended from time to time: (A) Executive
     Order 11246, as amended by Executive Order 11375, including 41 CFR Part
     60.1 et seq. and 48 CFR 52.222-26, Equal Opportunity; (B) the
     Rehabilitation Act of 1973 (29 USC 793), as amended, including 41 CFR Part
     60-741 et seq. and 48 CFR 52.222-36, Affirmative Action for Workers With
     Disabilities; (C) the Vietnam Era Veterans Readjustment Assistance Act of
     1974 (38 USC 4212), including 41 CFR Part 60-250 et seq. and 48 CFR
     52.222-35, Equal Opportunity for Special Disabled Veterans, Veterans of the
     Vietnam Era, and Other Eligible Veterans; (D) the certification
     requirements for nonsegregated facilities as ordered by the Secretary of
     Labor (32 F.R. 7439) and as required by 41 CFR Part 60-1 et seq.; (E)
     Executive Order 11141 (proscribing age discrimination); (F) the Service
     Contract Act of 1965, as amended (41 USC 351 et seq.) including 48 CFR
     52.222-41; (G) 48 CFR 52.237-7, Indemnification and Medical Liability
     Insurance; and (H) all regulations, rules, orders and applicable contract
     clauses promulgated under (A) through (G) above and/or required by federal,
     state or local law, rule or regulation to be included in this Agreement.
     Seller agrees that until four years after payment under this Agreement
     Seller will afford the Secretary of Health and Human Services, Comptroller
     General of the United States or any of their duly authorized
     representatives, access to, and the right to examine, any pertinent books,
     documents, papers and records of the successful bidder or offer or
     involving transactions relating to this Agreement.

18.0 CONFIDENTIALITY
     In the performance of this Agreement, each party will obtain knowledge
     about the other party and its operations. Seller and Quest Diagnostics
     acknowledge that they have entered into a Confidentiality Agreement dated
     November 21, 1996 (the "Confidentiality Agreement"), which Confidentiality
     Agreement, in the absence of the modification thereto set forth below,
     would have remained in effect with respect to its subject matter for two
     years after the termination of the Agreement between the parties dated
     January 1, 2000 (the "January 2000 Agreement") pursuant to Section 13.1 of
     the January 2000 Agreement, which terminated December 31, 2002. The parties
     agree to extend the protections and restrictions on use and disclosure of
     confidential information contained in the Confidentiality Agreement to all
     disclosures made under this Agreement, and by executing this Agreement,
     hereby modify the Confidentiality Agreement so that it shall remain
     effective until three (3) years after the expiration or sooner termination
     of this Agreement. The parties further hereby modify the Confidentiality
     Agreement so that any Confidential Information of a party (as defined in
     the Confidentiality Agreement) disclosed to the other party or to which the
     other party is provided access may only be used by the other party in
     furtherance of the purposes of this Agreement and subject to the
     restrictions contained in the Confidentiality Agreement. The parties
     acknowledge the terms, conditions and other contents of this Agreement,
     including all attachments incorporated into this Agreement, are
     confidential and subject to the Confidentiality Agreement and shall not be
     disclosed by either party except (i) to those individuals at or
     representatives or agents of the respective parties with a need to know
     such information who shall be subject to confidentiality obligations
     similar to those in this Agreement; (ii) as required by applicable law or
     regulation or Court Order or subpoena; (iii) based

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     upon mutual agreement of the parties, signed by authorized representatives
     of the parties, which agreement shall clearly delineate the terms of any
     such disclosures.

19.0 PRESS RELEASE
     Subject to the confidentiality provisions above, the parties agree that
     either party may issue a press release announcing the execution of this
     Agreement and related matters in form and substance satisfactory to and
     approved by both parties in writing, such approval not to be unreasonably
     withheld by either party.

20.0 INDEPENDENT CONTRACTORS
     It is understood that Quest Diagnostics and Seller are independent
     contractors engaged in the operation of their own respective businesses.
     Neither party is, or is to be considered as, the agent or employee of the
     other party for any purposes whatsoever. Neither party has authority to
     enter into contracts or assume any obligations for or on behalf of the
     other party or to make any warranties or representations for or on behalf
     of the other party.

21.0 SEVERABILITY
     It is the intention of the parties that the provisions of this Agreement
     will be enforceable to the fullest extent permissible under applicable
     laws, and that the unenforceability of any provisions under such laws will
     not render unenforceable, or impair, the remainder of this Agreement. If
     any provisions hereof are deemed invalid or unenforceable, this Agreement
     will be deemed amended to delete or to modify, as necessary, the offending
     provisions and to alter the bounds thereof in order to render it valid and
     enforceable.

22.0 FORCE MAJEURE
     No delay in or failure of performance by either party under this Agreement
     will be considered to be a breach hereof if and to the extent that an
     occurrence or occurrences beyond the control of the party affected caused
     such delay or failure of performance, including delay due to shortage of
     materials, labor difficulties, floods, fires, actions taken or threatened
     by any governmental agencies, terrorism, civil unrest, acts of God or other
     contingencies or acts not within the sole control of the party. Cytyc
     reserves the right (a) during the period of any shortage to allocate its
     available supplies it may determine equitable without any liability to
     Customer, and (b) to make substitutions and modifications in the
     specification of any Product, provided such substitutions or modifications
     do not materially affect the performance of Products. The foregoing will
     not be considered to be a waiver of either party's obligations under this
     Agreement, and as soon as such occurrence or occurrences cease, the party
     affected thereby will promptly fulfill its obligations under this Agreement
     which accrued during such occurrence or occurrences.

23.0 PARTICIPATION IN FEDERALLY FUNDED HEALTHCARE PROGRAMS
     Each party to this Agreement represents that (i) it has not been convicted
     of a criminal offense related to health care, or (ii) is not currently
     listed by a federal agency as debarred, excluded or otherwise ineligible
     for participation in federally funded health care programs. Either party
     shall notify the other in writing within five (5) days of any change in
     this representation or if circumstances change to render this
     representation false during the term of this Agreement. Such change in
     circumstances shall constitute cause by the other party to immediately
     terminate this Agreement. For purposes of this paragraph, a party is
     defined as the entities entering into this contract, and/or its principals,
     directors and officers.

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24.0 DISPUTES
     All disputes, controversies or claims arising out of or under this
     Agreement or its performance shall be resolved as set forth in this
     Section.

24.1 Arbitration
     Except for clauses 11.3 and 11.4 above and alleged breaches of
     confidentiality obligations or intellectual property rights, any
     controversy or claim arising out of or related to any Product, this
     Agreement, or the breach thereof in which the amount in controversy is less
     than $3 million, exclusive of interest and attorney's fees, shall be
     settled by binding arbitration, by a single arbitrator mutually agreeable
     to the parties (if the amount in controversy is less than $1 million
     exclusive of interest and attorney's fees), administered by the American
     Arbitration Association ("AAA") in accordance with the AAA's Commercial
     Arbitration Rules, including the Emergency Interim Relief Procedures, and
     judgment on the award rendered by the arbitrator may be entered in any
     court having jurisdiction thereof. In the event that a claim exceeds $1
     million and is less than $3 million, exclusive of interest and attorneys
     fees, the dispute shall be heard and determined by three arbitrators; Quest
     Diagnostics and Cytyc each selecting one arbitrator, and the two mutually
     selecting a third neutral arbitrator. Any arbitration under this clause
     shall be held in New York, New York and the arbitrator shall have no
     authority to award punitive, consequential, or other damages not measured
     by the prevailing party's actual damages. Each party shall bear its own
     costs and expenses and an equal share of the arbitrators' and
     administrative fees of arbitration. The parties acknowledge that this
     agreement evidences a transaction involving interstate commerce. The
     Federal Arbitration Act shall govern the interpretation, enforcement, and
     proceeding under this arbitration clause. If any of these provisions shall
     be held to be invalid, illegal or unenforceable, the validity, legality and
     enforceability of the remaining provisions shall not in any way be affected
     or impaired.

24.2 Civil Litigation
     Any dispute in which the amount in controversy is $3 million or more,
     exclusive of interest and attorney's fees, may be resolved in any state or
     federal court in which jurisdiction and venue are proper. The parties
     hereby irrevocably waive, to the fullest extent permitted by law, all
     rights to trial by jury in any action, proceeding or counterclaim (whether
     in contract, statute, tort (including negligence) or otherwise) relating to
     or arising from this Agreement. In any litigation, each party shall bear
     its own fees and expenses, including attorneys' fees.

24.3 Governing Law
     This Agreement shall be governed by and interpreted in accordance with the
     laws of the State of New York without regard to the conflict of laws
     principles of such State.

25.0 ENTIRE AGREEMENT
     This Agreement, the Confidentiality Agreement and the Service Agreement
     constitute the entire Agreement and supercede all prior written or oral
     agreements between Quest Diagnostics (including its Majority Owned
     Subsidiaries) with respect to the subject matter hereof. No modification of
     this Agreement will have any force or effect unless such modification is in
     writing and signed by authorized representatives of both parties. This
     Agreement is valid only when signed by authorized representatives of both
     companies and both parties have signed within ten (10) days of each other.

26.0 NOTICES
     Any notice required to be given hereunder will be deemed to have been
     served properly, if sent by a nationally recognized overnight express
     carrier or mailed by certified mail, postage prepaid,

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     properly addressed and posted in a United States depository to the
     respective parties hereto at the following addresses. Notices shall be
     effective upon receipt.

     To Quest Diagnostics:   1201 South Collegeville Road
                             Collegeville, PA 19426
                             Attention: Sourcing Manager, Commodity

     With a copy to:         1201 South Collegeville Road
                             Collegeville, PA 19426
                             Attention: Deputy General Counsel

     To Seller:              85 Swanson Road
                             Boxborough, MA 01719
                             Attention: VP Commercial Operation

     With a copy to:         85 Swanson Road
                             Boxborough, MA 01719
                             Attention: National Account Director (Quest)

                             85 Swanson Road
                             Boxborough, MA 01719
                              Attention: General Counsel's Office

27.0 WAIVER; NON-EXCLUSIVE REMEDY
     No waiver of any breach or failure by either party to enforce any of the
     terms or conditions of this Agreement at any time will, in any manner,
     limit or waive such party's right thereafter, to enforce and to compel
     strict compliance with every term and condition hereof. No remedy made
     available to any party by any of the provisions of this Agreement is
     intended to be exclusive of any other remedy, and each and every remedy
     will be cumulative and in addition to every other remedy available under
     this Agreement, at law, in equity, or otherwise.

28.0 USE OF MARKS
     During the Term of this Agreement, Seller grants Quest Diagnostics a fully
     paid up right and license to use its Trademarks referenced in Exhibit 29.0
     solely in connection with Quest Diagnostics' promotion, marketing and
     distribution of the Products, provided that Quest Diagnostics' use of the
     Trademarks is lawful and in accordance with the trademark usage guidelines
     provided by Seller attached hereto as Exhibit 29.0 and incorporated by
     reference herein. Said guidelines may be revised from time to time during
     the term in the sole discretion of Seller with thirty (30) days written
     notice to Quest Diagnostics. During the term of this Agreement, Quest
     Diagnostics grants Cytyc the right to use the Quest Diagnostics' trademark
     solely in promotional materials for the sole purpose of identifying that
     Quest Diagnostics performs the Test. Except as permitted by the preceding
     sentence, Seller shall not mention or otherwise use any name, insignia,
     symbol, trademark, trade name or logotype of Quest Diagnostics (or any
     abbreviation or adaptation thereof) in any publication, press release,
     promotional material or other form of publicity other than as required by
     law or regulation without the prior written approval of Quest Diagnostics.
     In the event such approval is granted by Quest Diagnostics, such usage
     together with usage of the Quest Diagnostics' trademark shall be lawful and
     in accordance with trademark usage guidelines provided by Quest Diagnostics
     and any goodwill or other benefit accruing from such usage shall accrue
     solely to Quest Diagnostics. Said guidelines may be

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     revised from time to time during the term in the sole discretion of Quest
     Diagnostics with thirty (30) days written notice to Seller. Upon
     termination of this Agreement, each party shall discontinue the use of the
     other's trademarks that it has been authorized to use under this Agreement.
     The restrictions imposed by this Section shall not prohibit either party
     from making any disclosure identifying the other party that is required by
     applicable law.

29.0 COUNTERPARTS
     This Agreement may be executed in one or more counterparts, including by
     facsimile, all of which shall be considered one and the same agreement. The
     Agreement shall become effective when each party has signed and delivered
     to the other party at least one such counterpart.

30.0 SURVIVAL
     The provisions of Sections 10.2, 11, 14, 16, 17, 18, 19, 24, 26 and 28
     shall survive termination of this Agreement.

     IN WITNESS WHEREOF, the parties intending to be legally bound, do hereby
     execute this Agreement and represent that the individuals executing this
     Agreement have authority to bind the respective entities.

     CYTYC CORPORATION                       QUEST DIAGNOSTICS INCORPORATED


     BY:                                     BY:
     -------------------------------------   -----------------------------------

     PRINT NAME:                             PRINT NAME:
     -------------------------------------   -----------------------------------

     TITLE:                                  TITLE:
     -------------------------------------   -----------------------------------

     DATE:                                   DATE:
     -------------------------------------   -----------------------------------


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                                  EXHIBIT 1.1

                             New Equipment Purchase

ThinPrep(TM) 2000 Processor

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------
            ITEM                              DESCRIPTION                PART NO.     Price
---------------------------------------------------------------------------------------------
<S>                                <C>                                   <C>         <C>
ThinPrep(TM) 2000 Processor        TP 2000 Processor used to process     70031-001   [______]
                                   gynecological and non-
                                   gynecological slide samples.
                                   (Includes one accessory kit and one
                                   year service warranty.)

---------------------------------------------------------------------------------------------
</TABLE>

ThinPrep(TM) 3000 Processor

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------
            ITEM                              DESCRIPTION                PART NO.     Price
---------------------------------------------------------------------------------------------
<S>                                <C>                                   <C>         <C>
ThinPrep(TM) 3000 Processor        TP 3000 Processor used to process     70150-001   [______]
                                   gynecological and non-
                                   gynecological slide samples.
                                   (Includes one accessory kit and one
                                   year service warranty.)

---------------------------------------------------------------------------------------------
</TABLE>

[________]

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      Equipment Rental (Existing Unilab Equipment Attached as Exhibit 1.1A)

ThinPrep(TM) 2000 Processor

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------
            ITEM                              DESCRIPTION                PART NO.     Price
---------------------------------------------------------------------------------------------
<S>                                <C>                                   <C>         <C>
ThinPrep(TM) 2000 Processor        TP 2000 Processor used to process     70031-001   [______]
                                   gynecological and non-
                                   gynecological slide samples.
                                   (Includes one accessory kit, any
                                   applicable one-year warrantyand
                                   full service for term of
                                   Agreement.)

---------------------------------------------------------------------------------------------
</TABLE>

ThinPrep(TM) 3000 Processor

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------
            ITEM                              DESCRIPTION                PART NO.     Price
---------------------------------------------------------------------------------------------
<S>                                <C>                                   <C>         <C>
ThinPrep(TM) 3000 Processor        TP 3000 Processor used to process     70150-001   [______]
                                   gynecological and non-
                                   gynecological slide samples.
                                   (Includes one accessory kit, any
                                   applicable one-year warranty,and
                                   full service for term of
                                   Agreement.)

---------------------------------------------------------------------------------------------
</TABLE>

Unilab Equipment Rental:
Unilab Equipment shall be rented at the above rates for the term of the
Agreement. The above payments shall include full service during the term of the
Agreement pursuant to the terms of the Service Agreement. Upon expiration of the
term or sooner termination of this Agreement, Quest Diagnostics shall return the
Unilab Equipment at its expense.

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                                                                   Page 19 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

                        New Equipment Rent to Own Option

ThinPrep(TM) 2000 Processor

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------
            ITEM                              DESCRIPTION                PART NO.     Price
---------------------------------------------------------------------------------------------
<S>                                <C>                                   <C>         <C>
ThinPrep 2000(TM) Processor        TP 2000 Processor used to process     70031-001   [______]
                                   gynecological and non-
                                   gynecological slide samples.
                                   (Includes one accessory kit,
                                   one-year warranty and one year full
                                   service)

---------------------------------------------------------------------------------------------
</TABLE>

ThinPrep 3000(TM) Processor

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------
            ITEM                              DESCRIPTION                PART NO.     Price
---------------------------------------------------------------------------------------------
<S>                                <C>                                   <C>         <C>
ThinPrep(TM) 3000 Processor        TP 3000 Processor used to process     70150-001   [______]
                                   gynecological and non-
                                   gynecological slide samples.
                                   (Includes one accessory kit,
                                   one-year warranty,and one-year full
                                   service)

---------------------------------------------------------------------------------------------
</TABLE>

Rent to Own Option:
Rent to Own option is for 24 months from the date of shipment with one year
warranty and one year full service pursuant to the Service Agreement [_____]. At
the end of the twenty four months, if Quest Diagnostics has paid all monies owed
to Cytyc with respect to the rental payments during the term, and is not in
material breach of this Agreement, title to the Equipment shall pass from Cytyc
to Quest Diagnostics free and clear of all liens and encumbrances thereon.
Otherwise, Quest Diagnostics shall return the Instruments to Cytyc at the end of
the twenty-four month period at Quest Diagnostics' expense. This provision will
survive any early termination of this Agreement.

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                                                                   Page 20 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

                                  EXHIBIT 1.1A

                              Unilab Equipment T-2

                                    [_____]

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                                                                   Page 21 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

                                  EXHIBIT 1.1A

                              Unilab Equipment T-3

                                    [_____]

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                                                                   Page 22 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

                                  EXHIBIT 2.1

                             Reagents and Supplies

Price per Test from effective date through December 31, 2003:

Full Kit Lab Kit Phys. Kit
[_____]  [_____]  [_____]

Price per Test from January 1 2004 through April 30, 2005 or the termination of
this Agreement:

Full Kit Lab Kit Phys. Kit
[_____]  [_____]  [_____]

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                                                                   Page 23 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------
THINPREP PAP TEST SUPPLIES
------------------------------------------------------------------------------------------------------
<S>         <C>                                                         <C>
70096-001   ThinPrep(R) Pap Test Package                                [_____] per package from
            Includes: 500 tests and 500 Broom-like collection devices   5/1/03 through 12/31/03

                                                                        [_____] per package from
                                                                        1/1/04 through 4/30/05 or
                                                                        termination of this
                                                                        Agreement
------------------------------------------------------------------------------------------------------
70096-003   ThinPrep Pap Test  Package                                  [_____] per package from
            Includes: 500 tests and 500 Cytobrush/Plastic               5/1/03 through 12/31/03
            Spatula collection devices

                                                                        [_____] per package from
                                                                        1/1/04 through 4/30/05 or
                                                                        termination of this
                                                                        Agreement
------------------------------------------------------------------------------------------------------
70136-001   Physician's Kit                                             [_____] per package
            Includes: 500 vials and 500 Broom-like collection devices
------------------------------------------------------------------------------------------------------
70136-002   Physician's Kit                                             [_____] per package
            Includes: 500 vials and 500 Cytobrush/Plastic Spatula
            collection devices
------------------------------------------------------------------------------------------------------
70137-001   Laboratory Kit                                              [_____] per package from
            Includes: 500 filters and 500 slides                        5/1/03 through 12/31/03

                                                                        [_____] from 1/1/04 through
                                                                        4/30/05 or termination of this
                                                                        Agreement
------------------------------------------------------------------------------------------------------
70101-001   Broom-like Collection Devices                               [_____]per package
            Includes: 500 Broom-like collection devices
------------------------------------------------------------------------------------------------------
70124-001   Cytobrush/Spatula Collection Devices                        [____] per package
            Includes: 500 Cytobrush/Plastic Spatula collection devices
------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------
NON-GYN SUPPLIES
------------------------------------------------------------------------------------------------------
<S>         <C>                                                         <C>
70205-001   Non-Gyn TransCyt Filters                                    [_____] box
            Box of 100 filters
------------------------------------------------------------------------------------------------------
70214-001   ThinPrep Slides, box of 100 slides                          [_____] per box
                                                                        [____] per case of [__] boxes
------------------------------------------------------------------------------------------------------
0100007     Multi-Mix Racked Vortexor                                   [_____] each
------------------------------------------------------------------------------------------------------
0234005     PreservCyt Solution, vials                                  [_____] box
            Box of 50 vials, pre-filled with 20 ml
------------------------------------------------------------------------------------------------------
0234004     PreservCyt Solution, 32 oz bottles                          [_____] box
            Box of 4, 32 oz. Bottles
------------------------------------------------------------------------------------------------------
0236004     CytoLyt(R) Solution, 32 oz bottles                          [_____] box
            Box of 4, 32 oz. Bottles
------------------------------------------------------------------------------------------------------
</TABLE>

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                                                                   Page 24 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------
<S>         <C>                                                         <C>
0236080     CytoLyt Solution, centrifuge tubes                          [_____] box
            Box of 80 centrifuge tubes, pre-filled with 30 ml
------------------------------------------------------------------------------------------------------
0236050     CytoLyt Solution, collection cups                           [_____] box
            Box of 50 collection cups, pre-filled with 30 ml
------------------------------------------------------------------------------------------------------
</TABLE>

THINPREP 2000 PROCESSOR ACCESSORIES

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------
<S>         <C>                                                         <C>
70102-001   ThinPrep2000 Processor Operator's Manual And Updates        Provided free of charge on
                                                                        purchase or lease of
                                                                        Equipment--Additional
                                                                        copies [_____]
------------------------------------------------------------------------------------------------------
50705-001   Dispenser Pump, for use with 32 oz bottles                  [_____] each
------------------------------------------------------------------------------------------------------
70129-001   Fix Bath Vials                                              [_____] each
------------------------------------------------------------------------------------------------------
70027-001   Filter Cap Assembly                                         [_____] each
------------------------------------------------------------------------------------------------------
74024-001   O-Rings for Filter Cap, package of 10                       [_____] package
------------------------------------------------------------------------------------------------------
50248-001   Waste Filter                                                [_____] each
------------------------------------------------------------------------------------------------------
50326-001   Vacuum Grease                                               [_____] each
------------------------------------------------------------------------------------------------------
74023-001   Waste Tubing Replacement Kit, includes 2 pre-cut tubes      [_____]per kit
------------------------------------------------------------------------------------------------------
</TABLE>

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                                                                   Page 25 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

                                  EXHIBIT 12.3

                               Service Agreement

1.   General. Customer and Cytyc Corporation ("Cytyc") are parties to an
     Agreement for Purchase of Equipment, Reagents and Supplies effective as of
     May 1, 2003 (the "Purchase Agreement"), under which Customer purchases or
     leases from Cytyc and Cytyc sells or leases to Customer certain Equipment,
     Reagents and Supplies identified in the Purchase Agreement (including
     existing Unilab Equipment within the meaning of the Purchase Agreement). In
     addition, Customer owns the Equipment identified on Exhibit A attached
     hereto (that Equipment, together with all Equipment purchased or leased by
     Customer under the Purchase Agreement, shall hereafter be referred to as
     "Equipment"). Equipment purchased or leased under the Purchase Agreement as
     well as certain of the existing Equipment owned or leased by Customer is
     under a twelve month manufacturer's warranty under the Purchase Agreement.
     The parties are entering into this Agreement to set forth the terms under
     which Cytyc will service and maintain in good working order and condition
     all Equipment the warranty for which has expired or will expire during the
     term of this Agreement (the "Covered Equipment"). These terms and the terms
     of the Purchase Agreement constitute the entire contract between the
     parties regarding service for Covered Equipment and supersede all prior
     written and oral agreements, understandings and representations. Each party
     agrees that the terms and conditions for the sale or lease of Equipment
     contained in any purchase order, confirmation, invoice or other unilateral
     document issued by a party in connection herewith, which are in addition to
     or inconsistent with this Agreement, will not be deemed to affect or modify
     this Agreement.

2.   Service. Cytyc shall provide to Customer during the term hereof, preventive
     maintenance in accordance with specifications and repair service on Covered
     Equipment (the "Covered Service"). All Covered Service shall be provided by
     properly trained Cytyc Field Service Engineers. Covered Service shall be
     provided during normal service hours between 8:30 AM through 5:30 PM,
     Monday through Friday, except Cytyc holidays. All labor and replacement
     Equipment or part(s) for Covered Equipment that fails for any reason other
     than those set forth below are included in the Covered Service. Unless
     otherwise specified, one preventive maintenance visit per unit of Covered
     Equipment per year is included in the Covered Service. Customer shall be
     responsible for performing routine maintenance in accordance with the
     applicable Operator's Manual to the extent the Operator's Manual specifies
     that Customer perform such routine maintenance. Customer agrees to make
     Covered Equipment available to Cytyc at mutually acceptable prearranged
     times in order for Cytyc to perform the Covered Service. The Covered
     Service does not include the following: (1) service or parts which are
     needed as a result of Customer's negligence, misuse, theft, environmental
     factors, unauthorized modifications or accessory items not meeting Cytyc's
     specifications, or any other cause beyond Cytyc's control, including
     floods, fires, acts of God or any other contingencies or acts not within
     the sole control of Cytyc; (2) replacement of Covered Equipment supplies,
     including but not limited to waste bottles, filter caps, o-rings, tubing
     and other consumables and (3) reconditioning or refurbishment of Covered
     Equipment covered by this Agreement.

3.   Payment/Price. [_____] Any additional service not specifically covered
     under this Agreement shall be at Cytyc's option and shall be paid for by
     Customer at Cytyc's then current hourly rate for service and its then
     current rate for parts. When applicable for additional services not covered
     by this Agreement, Customer agrees to pay Cytyc the undisputed portion of
     any fee for service or parts and any applicable taxes, within thirty (30)
     days of receipt of the invoice. Prices for parts are FOB Boxborough, MA.
     Customer is responsible for all shipping charges for parts not covered by
     this Agreement. Cytyc reserves the right to charge interest on all
     undisputed amounts not paid by the date due, at the lower of 12% per annum
     or the maximum rate permitted by law. Payment of disputed amounts is not
     binding as a resolution of disputed issues, absent written authorization
     from Cytyc's General Counsel.

4.   Delays in Performance. Cytyc shall not be liable for failure or delay in
     providing service or in the shipment of parts by reason of shortage of
     materials, labor difficulties, floods, fires, actions taken or threatened
     by any governmental agencies, acts of God or other contingencies or acts
     not within the sole control of Cytyc.

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                                                                   Page 26 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

5.   Limited Warranty & Limitation of Liability. All service provided hereunder
     shall be performed in a timely, professional and workmanlike manner, by
     qualified personnel in accordance with general industry standards and
     procedures for similar services, and in accordance with manufacturer
     specifications and all federal, state and local laws, rules, regulations
     and orders. Cytyc further warrants that Covered Equipment shall be
     maintained by Cytyc in accordance with generally accepted industry
     standards and Covered Equipment will perform in accordance with all
     applicable federal and state laws, regulations and guidelines (including
     applicable U.S. Food and Drug Administration regulations and guidelines),
     with published specifications and with any additional documentation
     provided by Cytyc including package inserts during the term of this
     Agreement. Cytyc's sole obligation under this warranty is to repair or
     replace (at its sole discretion) any Covered Equipment or part thereof that
     is deemed to be defective. Cytyc shall repair or replace at its sole
     expense any defective Covered Equipment as promptly as is practicable. If
     Cytyc elects to repair Covered Equipment, and such repair cannot be
     completed within five (5) business days, Cytyc shall provide Quest
     Diagnostics with loaner Equipment in good working order until such repair
     can be completed. In fulfilling its obligation to provide loaner Equipment
     for ThinPrep(TM) 3000 Equipment, Cytyc may provide one (1) ThinPrep 2000
     Processor up to a maximum of two (2) ThinPrep(TM) 2000 Processors in
     accordance with Customer's volume requirements in lieu of providing a
     ThinPrep(TM) 3000 Processor. If the defective Covered Equipment is leased
     Equipment, and the Covered Equipment is not repaired or loaner Equipment
     provided within five (5) business days after the defect arose, [_____].
     Cytyc shall be responsible for the expense of returning nonconforming
     Covered Equipment or parts, and providing conforming Covered Equipment or
     parts in exchange. This warranty shall not apply to defects resulting from
     misuse, negligence or accident, including, without limitation: operation
     outside of the environmental specifications for the Product; use of
     unauthorized supplies; performance of improper or inadequate maintenance
     specified to be performed by Customer in the Operator Manual for the
     Covered Equipment; installation of software not supplied by Cytyc; improper
     use or connection to incompatible equipment; making of modifications to the
     Product not authorized by Cytyc; and external causes such as, but not
     limited to, power failure. THE FOREGOING PROVISIONS SET FORTH CYTYC'S SOLE
     AND EXCLUSIVE REPRESENTATIONS, WARRANTIES AND OBLIGATIONS WITH RESPECT TO
     THE SERVICE OF THE COVERED EQUIPMENT AND THE PARTS PROVIDED, AND CYTYC
     MAKES NO OTHER WARRANTY OF ANY KIND WHATSOEVER, EXPRESS OR IMPLIED. CYTYC
     SPECIFICALLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
     FITNESS FOR A PARTICULAR PURPOSE, WHETHER ARISING FROM A STATUTE OR
     OTHERWISE IN LAW, EQUITY OR FROM A COURSE OF DEALING OR USAGE OF TRADE.
     CYTYC'S LIABILITY ARISING OUT OF THE SERVICE PERFORMED UNDER THIS AGREEMENT
     AND THE REPLACEMENT PARTS FURNISHED HEREUNDER, WHETHER BASED UPON WARRANTY,
     CONTRACT, TORT OR OTHERWISE, SHALL NOT EXCEED THE ACTUAL PURCHASE PRICE
     PAID BY QUEST DIAGNOSTICS FOR THE COVERED EQUIPMENT AND SERVICES EXCEPT AS
     PROVIDED IN SECTIONS 11.3 OR 11.4 OF THE PURCHASE AGREEMENT. CYTYC
     ACKNOWLEDGES THAT SERVICES PROVIDED HEREUNDER SHALL BE SUBJECT TO THE
     INDEMNIFICATION PROVISIONS CONTAINED IN SECTIONS 11.3 AND 11.4 OF THE
     PURCHASE AGREEMENT. EXCEPT FOR THOSE INDEMNIFICATION OBLIGATIONS, IN NO
     EVENT SHALL EITHER PARTY BE LIABLE FOR LOST PROFITS, RELIANCE, INDIRECT,
     INCIDENTAL, CONSEQUESTIAL OR SPECIAL DAMAGES AND THIS CLAUSE SHALL
     CONSTITUTE A COMPLETE DEFENSE TO SUCH CLAIMS. SUCH LIMITED WARRANTY IS
     GIVEN SOLELY TO THE ORIGINAL CUSTOMER AND IS NOT GIVEN TO, NOR MAY IT BE
     RELIED UPON BY, ANY THIRD PARTY INCLUDING, WITHOUT LIMITATION, CUSTOMERS OF
     CUSTOMER. THIS WARRANTY IS VOID UPON TRANSFER OF COVERED EQUIPMENT BY
     CUSTOMER TO ANY ENTITY WHO HAS LESS THAN FIFTY (50) PERCENT OWNERSHIP IN
     THE COVERED EQUIPMENT. SOME STATES DO NOT ALLOW THE EXCLUSION OF IMPLIED
     WARRANTIES SO THE ABOVE EXCLUSIONS MAY NOT APPLY TO YOU. YOU MAY ALSO HAVE
     OTHER RIGHTS, WHICH VARY, FROM STATE TO STATE.

6.   Term and Termination. This Agreement shall have a term commencing May 1,
     2003 and continuing for the term of the Purchase Agreement; provided,
     however, that with respect to leased Covered Equipment, should the 24 month
     period of the lease extend beyond the term of the Purchase Agreement, this
     Agreement shall continue

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                                                                   Page 27 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

     for so long as such lease continues with respect to such Covered Equipment.
     Either party shall have the right to terminate this Agreement in the event
     that the other party shall default on or materially breach any provision
     hereof that is not cured within thirty (30) days of notice thereof.

7.   Notice. Any required notice shall be given in writing to each party as
     provided in the Purchase Agreement.

8.   Amendments. This Agreement may be modified only by written amendment
     referring to this Agreement and signed by persons authorized to sign on
     behalf of the parties. If any of these contractual provisions are held
     invalid, illegal or unenforceable, the validity, legality and
     unenforceability of the remaining provisions shall not in any way be
     affected or impaired.

9.   Assignability and Waiver. This Agreement may only be assigned in accordance
     with the provisions of the Purchase Agreement. Either party's failure to
     exercise any of its rights hereunder shall not constitute or be deemed a
     waiver or forfeiture of such rights or any rights hereunder.

10.  Choice of Law and Enforcement. If any of these provisions shall be held to
     be invalid, illegal or unenforceable, the validity, legality and
     enforceability of the remaining provisions shall not in any way be affected
     or impaired. This Agreement shall be governed by and interpreted in
     accordance with the laws of the State of New York without regard to the
     conflict of laws principles of such State. The parties agree that any
     disputes hereunder shall be resolved in accordance with the provisions of
     Section 24 of the Purchase Agreement.

Accepted and agreed to effective this 1st day of May, 2003:

Quest Diagnostics Incorporated           Cytyc Corporation

By:                                      By:
   -----------------------------------      ------------------------------------

Name:                                    Name:
     ---------------------------------        ----------------------------------

Title:                                   Title:
      --------------------------------          --------------------------------

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                                                                   Page 28 of 29

<PAGE>

[LOGO] Quest Diagnostics(R)

                         EXHIBIT A to Service Agreement

                    Quest T2000 Owned Equipment by Location

                                    [_____]

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                                                                   Page 29 of 29