<PAGE>

                            ASSET PURCHASE AGREEMENT

                                  BY AND AMONG

                                  VYSIS, INC.,

                              GENE-TRAK, INC., and

              GENE-TRAK SYSTEMS INDUSTRIAL DIAGNOSTICS CORPORATION

                            (collectively "SELLERS")

                                       and

                               NEOGEN CORPORATION

                                 AUGUST 4, 2001
<PAGE>

                                TABLE OF CONTENTS

                                                                            Page
                                                                            ----

ARTICLE I.    DEFINITIONS.....................................................1

ARTICLE II.   PURCHASE AND SALE...............................................3

   2.1        Sale and Purchase of Assets.....................................3
   2.2        Assumption of Liabilities.......................................4

ARTICLE III.  PURCHASE PRICE; CLOSING.........................................4

   3.1        Purchase Price..................................................4
   3.2        Closing.........................................................4
   3.3        Transaction Taxes...............................................5
   3.4        Form of Delivery................................................5
   3.5        Rebate of Lease Savings.........................................5

ARTICLE IV.   REPRESENTATIONS AND WARRANTIES OF SELLERS.......................6

   4.1        Organization, Standing and Power................................6
   4.2        Authority.......................................................6
   4.3        Consents and Approvals..........................................6
   4.4        Litigation, Claims, Violations..................................6
   4.5        Intellectual Property...........................................7
   4.6        Assigned Properties.............................................8

ARTICLE V.    REPRESENTATIONS AND WARRANTIES OF NEOGEN.......................14

   5.1        Organization, Standing and Power...............................14
   5.2        Authority......................................................14
   5.3        Consents and Approvals.........................................14

ARTICLE VI.   BUSINESS TRANSFER................................................

   6.1        Orders/Technical Service Support...............................15
   6.2        Sales Transition...............................................15

   6.3        Operations at Hopkinton

   6.4        Management Information Systems (MIS)

   6.5        Transition Costs

ARTICLE VII.  LICENSE COVENANTS  16

   7.1        Grant of Exclusive License.....................................16
   7.2        Limitations....................................................16

ARTICLE VIII. CONTRACT ASSIGNMENT AND EMPLOYMENT MATTERS

   8.1        Contracts, Licenses and Service Agreements.....................17

                                                                             -i-
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   8.2        Assumption of Contract Obligations.............................17
   8.3        Employment.....................................................18

ARTICLE IX.   GENERAL COVENANTS..............................................18

   9.1        Access and Rights of Inspection................................18
   9.2        Further Assurances.............................................18
   9.3        Claims Handling................................................19
   9.4        Confidentiality Regarding Information of Business..............19
   9.5        Covenant Not to Compete........................................19

   9.6        Change of Corporate Names

   9.7        Avante Access

ARTICLE X.    SURVIVAL OF REPRESENTATIONS AND WARRANTIES;
              INDEMNIFICATION; ARBITRATION...................................21

  10.1        Survival of Representations and Warranties.....................23
  10.2        Indemnification by SELLERS.......................................
  10.3        Indemnification by NEOGEN........................................
  10.4        Damages..........................................................
  10.5        Assertion and Defense of Indemnification Claims..................
  10.6        Limitation on Recovery...........................................
  10.7        Limitation of Liability........................................23

ARTICLE XI.   MISCELLANEOUS..................................................24

  11.1        Successors; Assignability......................................24
  11.2        Costs and Expenses.............................................24
  11.3        Other Agreements Superseded; Waiver and Modification, Etc. ....24
  11.4        Notices........................................................24
  11.5        Parties in Interest............................................25
  11.6        Governing Law; Jurisdiction....................................25
  11.7        Fair Construction/Difference in Facts..........................25
  11.8        Captions, References, Date.....................................25
  11.9        Severability...................................................26
  11.10       Counterparts...................................................26
  11.11       Relationship of the Parties....................................26
  11.13       Brokerage......................................................26
  11.14       Publicity......................................................26
  11.15       Arbitration....................................................26
  11.16       Sole Remedy....................................................28

                                                                            -ii-
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                      Schedules and Exhibits


Schedules
---------

1      Business Assets
2      Assigned Contracts
2.1    Products of the Business
2.2    Assumed Liabilities
3      Assigned License and Immunities Agreements
4      Other Intangible Assets
5      Service Contracts
6      Outstanding Purchase Orders
7      Purchase Price Allocation
8      Exceptions to Representation and Warranties
9      Patents and Trademarks Used in the Business
10     Financials
11     Receivables
12     Employees
13     Benefit Plans
14     Governmental Permits


Exhibits
--------

       A   Bill of Sale
       B   Assignment Of Immunity From Suit Under Gen-Probe's Kohne Patents
       C   Assignment of Orion and Institut Pasteur Licenses
       D   Assignment of GENE-TRAK Licenses
       E   Press Announcement of Closing


                                                                           -iii-
<PAGE>

                            ASSET PURCHASE AGREEMENT

         This Asset Purchase Agreement (this "Agreement"), effective as of July
31, 2001, is made by and among Vysis, Inc. ("VYSIS"), a Delaware corporation
with its principal place of business at 3100 Woodcreek Drive, Downers Grove,
Illinois, Gene-Trak, Inc. ("GTI"), a Delaware corporation with its principal
place of business at 3100 Woodcreek Drive, Downers Grove, Illinois, Gene-Trak
Systems Industrial Diagnostics Corporation ("GENE-TRAK"), a Delaware corporation
with its principal place of business at 94 South St., Hopkinton, Massachusetts,
and Neogen Corporation ("NEOGEN"), a Michigan corporation with its principal
place of business at 620 Lesher Place, Lansing, Michigan 48912. VYSIS, GTI and
GENE-TRAK are collectively referred to herein as "SELLERS". The SELLERS and
NEOGEN are sometimes referred to herein as the "Parties."

                                    RECITALS
                                    --------

         WHEREAS, VYSIS owns all of the outstanding voting equity of GTI, and
GTI owns all of the outstanding voting equity of GENE-TRAK;

         WHEREAS, GENE-TRAK operates a DNA probe based food testing business;

         WHEREAS, certain of the intellectual property assets used by GENE-TRAK
in its food testing business are owned by VYSIS or GTI;

         WHEREAS, VYSIS, GTI and GENE-TRAK desire to sell certain assets of the
GENE-TRAK food testing business and to provide certain technology licenses for
the continued practice of the GENE-TRAK food testing business to NEOGEN on the
terms and conditions herein, and NEOGEN desires to purchase such assets and
acquire such licenses; and

         NOW, THEREFORE, in consideration of the above and the mutual promises
and covenants set forth below, SELLERS and NEOGEN agree as follows:

ARTICLE 1 DEFINITIONS

         For the purposes of this Agreement the following definitions shall
apply:

         "Affiliate" of a party means, with respect to any party, any other
person or entity that, directly or indirectly, controls, is controlled by or is
under common control with, that party; provided, however, that in each case any
such other person or entity shall be considered to be an Affiliate only during
the time such control exists. For purposes of this definition, "control"
(including, with correlative meaning, the terms "controlled by" and "under
common control with") means the possession, directly or indirectly, of the power
to direct and/or cause the direction of the management and policies of such
party, whether through the ownership of voting securities, by contract or
otherwise.
<PAGE>

         "Books and Records" means copies of specific books and records related
to any assets sold by SELLERS hereunder, including, without limitation, product
lists with list prices, selling prices, and cost of goods sold on a
country-by-country basis, all financial records, books, ledgers, supplier lists,
customer and marketing lists or databases, marketing plans, management plans,
distribution and reseller materials, advertising materials, manuals,
manufacturing records, quality control records, quality assurance records and
good manufacturing practices records, insofar as such items solely relate to the
Business. Books and Records shall not include (i) the incorporation records and
documentation for GTI and GENE-TRAK, (ii) any employee, employment or employee
benefit plan records or (iii) any bank account records.

         "Business" means SELLERS' food testing business operated as of the
Effective Date by GENE-TRAK that employs DNA probe-based technology in the Food
Testing Field.

         "Business Assets" means all tangible assets listed on Schedule 1,
attached hereto and made a part of this Agreement by this reference.

         "Closing" is defined in Section 3.2.

         "Contract" means any written contract, agreement, commitment, note,
bond, lease, mortgage, guaranty, license or any other written or oral
contractual obligation or commitment that is listed on Schedule 2, attached
hereto and made a part of this Agreement by this reference.

         "Food Testing Field" means the field of testing for organisms by
detecting or quantifying ribosomal nucleic acids of any and all materials
associated with the production or processing of foodstuffs or beverages
(including but not limited to water and milk) intended for human or animal
consumption in any or all phases of production. Food Testing Field shall not
include any clinical or research applications for human species involving
testing of tissue, blood and cellular samples and extracts therefrom.

         "Excluded Assets" means any and all assets, both tangible and
intangible, of SELLERS that are not expressly listed herein as sold to NEOGEN by
license grant, assignment or otherwise.

         "Intellectual Property Rights" means, collectively, all Patents, Trade
Secrets, Copyrights, moral rights, trade names, Trademarks, rights in trade
dress, rights in biological materials and all other intellectual property rights
and proprietary rights, whether arising under the laws of the United States or
any other state, country or jurisdiction, including without limitation all
rights or causes of action for infringement or misappropriation of any of the
foregoing. "Patents" means all patents rights and all right, title and interest
in all letters patent or equivalent rights and applications for letters patent
or rights, industrial and utility models, industrial designs, patents of
importation, patents of addition, certificates of invention and any indicia of
invention ownership issued or granted by any Governmental Entity, including
without limitation any reissue, extension, division, continuation or
continuation-in-part applications throughout the world. "Trade Secrets" mean all
right, title and interest in all trade secrets and trade secret rights arising
under the applicable common law, state law, federal law or laws of foreign
countries. "Copyrights" mean all copyright rights and all other literary
property and author rights, and all right, title and interest in all copyrights,
copyright registrations, certificates of copyright and copyrighted interests
throughout the world. "Trademarks" mean all trademark and service mark rights
arising under the applicable common

                                                                             -2-
<PAGE>

law, state law, federal law and laws of foreign countries, all right, title and
interest in all trademarks, service marks, trademark and service mark
applications and registrations and trademark and service mark interests
throughout the world.

         "License and Immunities Agreements" means the license and immunity
agreements listed on Schedule 3 attached hereto and made a part of this
Agreement by this reference.

         "Lien" means liens, pledges, claims, charges, security interests and
other restrictions or encumbrances of any nature whatsoever.

         "Other Assets" means the intangible assets listed on Schedule 4
attached hereto and made a part of this Agreement by this reference, including
(i) manufacturer's or vendor's warranties or guarantees relating to any asset
acquired hereunder, (ii) claims against any third party relating to any asset
assigned to NEOGEN hereunder, (iii) the GENE-TRAK product sales receivable,
which are owned by SELLERS as of the Closing Date,

         (iv) to the extent assignable, all governmental permits and licenses
used or employed by SELLERS solely in the Business, (v) SELLERS' rights in the
name "GENE-TRAK" and all derivations thereof, and its associated goodwill
throughout the world, , (vi) software, source code and computer programs
(including all current and historical data bases) which relate solely to the
Business, and (vii) the domain name www.genetraksys.com.

         "Service Contracts" means the contracts listed on Schedule 5 attached
hereto and made a part of this Agreement by this reference.

         "Transferred Copyrights" means all of the unregistered copyrights
listed on Schedule 4.

         "Transferred Trademarks" means all of the Trademark registrations
listed on Schedule 4.

         "Transferred Patents" means all of the Patents listed on Schedule 4.

ARTICLE 2 PURCHASE AND SALE

         2.1 Sale and Purchase of Assets. Subject to the terms and conditions
contained in this Agreement, SELLERS hereby sell, assign, transfer, and deliver
to NEOGEN all of SELLERS' right, title, and interest in and to all assets listed
on Schedules 1 (Business Assets), 2 (Assigned Contracts), 3 (License and
Immunity Agreements), 4 (Other Intangible Assets) and 5 (Service Contracts)
hereof (collectively, the "Acquired Assets") to NEOGEN on the Closing Date on
the terms and conditions as set out herein.

         (a) Rights Under Contracts. All of SELLERS' rights under any contract,
agreement, plan or arrangement relating exclusively to the Business and
identified in Schedule 2 shall be transferred to NEOGEN, subject to any
necessary consents of any third party. It is the intent of the parties hereto
that any customer orders received by SELLERS arising out of the operation of the
Business for shipment in the ordinary course of business following the Closing
Date be transferred to NEOGEN. Attached as Schedule 6 is a list as of the date
shown on the Schedule 6 of all outstanding customer orders, purchase orders, and
other customer commitments from SELLERS' customers of the Business.

                                                                             -3-
<PAGE>

         (b) Books and Records. Most of the Books and Records of the Business
are maintained in GENE-TRAK's Hopkinton facility. Books and Records that relate
solely to the Business shall be the subject of title transfer from SELLERS to
NEOGEN. Books and Records which do not solely relate to the Business transferred
hereunder shall be the subject of a paid-up, transferable, royalty-free,
unlimited right granted by SELLERS to NEOGEN for NEOGEN to use such Books and
Records in furtherance of the Business; provided that SELLERS shall have the
right to redact any information not related to the Business, including
information related to VYSIS' business. For Books and Records maintained at
VYSIS' Downers Grove facility, upon NEOGEN's request, VYSIS will provide NEOGEN
access to such Books and Records upon reasonable advance notice and during
normal business hours to review and copy such Books and Records.

         (c) There is no transfer of ownership, by license, assignment or
otherwise of any Excluded Asset.

         2.2 Assumption of Liabilities. NEOGEN shall not assume, expressly or
implicitly, pay, perform or discharge any debts, liabilities or obligations of
any nature of SELLERS, whether or not related to the Business, other than those
specifically listed in Schedule 2.2 ("Assumed Liabilities"). All the debts,
liabilities and obligations of SELLERS, whether fixed or contingent, accrued or
unaccrued, known or unknown shall continue to be the responsibility of SELLERS,
which shall pay, perform and discharge them in accordance with their terms, and
nothing contained in this Agreement shall be construed in any fashion as
imposing, directly or indirectly, responsibility for any such debt, liability
and obligation on NEOGEN except the Assumed Liabilities.

ARTICLE 3 PURCHASE PRICE; CLOSING

         3.1 Purchase Price. The purchase price payable by NEOGEN to SELLERS as
consideration for the sale, assignment, transfer, and delivery by SELLERS to
NEOGEN of the Acquired Assets, the grant of the licenses to NEOGEN and the
assumption by NEOGEN of Assumed Liabilities, on the terms and conditions set
forth herein, shall be U.S. Three Million Four Hundred Eighty Nine Thousand
Dollars ($3,489,000), (the "Purchase Price") paid by wire transfer on Monday,
August 6, 2001 to an account designated by SELLERS.

         3.2 Closing.

         (a) The closing of the purchase and sale of the Acquired Assets and
the consummation of the other transactions contemplated hereby shall be held at
the offices of NEOGEN's attorneys in Okemos, Michigan ("Closing"), unless NEOGEN
and SELLERS shall have agreed in writing to a different location. .The parties
agree that the effective date of completion of the transaction shall be as of
the close of business on July 31, 2001 ("Closing Date"). The parties agree that
all sales, expenses and other activity relating to the Business after the
Closing Date shall be for the credit of NEOGEN.

         (b) Signing Deliveries. At the August 3, 2001 signing of this Agreement
("Signing"), NEOGEN shall deliver the Purchase Price as specified in Paragraph
3.1 against delivery by SELLERS of such transfer documents relating to the sale
and transfer of the Acquired Assets as NEOGEN shall reasonably request,
including, without limitation, the Warranty Bill of Sale in the form attached
hereto as Exhibit A. At the Signing, SELLERS shall put NEOGEN into full

                                                                             -4-
<PAGE>

possession and enjoyment of Acquired Assets, subject to any third party
consents, and NEOGEN shall be fully and solely responsible for and perform when
due or discharge any Assumed Liability. At any time and from time to time after
the Signing, at the request of NEOGEN and without further consideration, SELLERS
shall execute and deliver such further instruments of sale, transfer,
conveyance, assignment, and confirmation and take such actions as are reasonably
necessary to transfer, convey, and assign to NEOGEN (or such wholly owned
subsidiary as NEOGEN may designate), and to confirm NEOGEN's title to or
interest in, the Acquired Assets. .

         3.3 Transaction Taxes.

         (a) Sales Tax. SELLERS shall be responsible for any and all sales and
other taxes, except for income taxes on NEOGEN, arising in connection with the
sale of the Acquired Assets.

         (b) Allocation of Consideration. NEOGEN and SELLERS will allocate the
Purchase Price among the Acquired Assets (the "Allocation") in accordance with
Schedule 7 to be attached to this Agreement at or prior to the Closing in a form
mutually agreeable to the parties. No party will take a position on any federal
or state tax return, before any governmental agency charged with the collection
of any income tax, or in any judicial proceeding that is in any way inconsistent
with the Allocation.

         3.4 Form of Delivery.

         (a) Patent and Trademark Assignment. SELLERS shall deliver to NEOGEN at
the Closing Date executed assignments of the Patents and Trademark registrations
and applications listed on Schedule 4, all in a form reasonably acceptable to
NEOGEN.

         (b) Customer Support Records. Upon NEOGEN's request, SELLERS will
provide NEOGEN's representatives access upon reasonable advance notice and
during normal business hours to all of the original product customer support
records maintained in VYSIS' Downers Grove facility for copying purposes. If
available, SELLERS will deliver electronic versions of the records desired by
Neogen.

         (c) Delivery Costs. All costs and liability for the shipment and
physical delivery of any Acquired Assets and any intangible assets shall be as
follows: Items to be delivered to NEOGEN's designated facility will be shipped
F.O.B. point of origin, with costs of transportation and insurance to be repaid
to SELLERS by NEOGEN. Risk of loss to all items will belong to NEOGEN upon the
Closing Date.

         3.5 Rebate of Lease Savings. VYSIS will retain responsibility for the
GENE-TRAK facility lease and its associated service contracts. NEOGEN will be
permitted to operate rent-free out of the GENE-TRAK facility through October 31,
2001. If VYSIS is successful in (a) negotiating an early termination of the
lease before its present January 2003 expiration date or (b) subletting the
facility for any period after November 1, 2001 up to lease termination, then it
will share with NEOGEN on a 50/50 basis any cost savings from the projected
$258,017 costs to carry the lease and associated services through their
completion. Any cost saving payment made to NEOGEN shall be considered a
reduction of the Purchase Price in the amount of such payment.

                                                                             -5-
<PAGE>

ARTICLE 4 REPRESENTATIONS AND WARRANTIES OF SELLERS

         SELLERS, jointly and severally, represent and warrant to NEOGEN the
following:

         4.1 Organization, Standing and Power. SELLERS are each a corporation
duly organized, validly existing and in good standing under the laws of the
State of Delaware. SELLERS each have the corporate power to own its properties
and to carry on its business as now being conducted. To SELLERS' knowledge, no
failure on the part of SELLERS to be qualified as foreign corporations in any
jurisdiction materially and adversely affects the Business or the financial
position or results of operations of the properties of the Business, by reason
of any disability affecting their respective right to own property, collect
receivables, enforce contracts or otherwise.

         4.2 Authority. SELLERS have all requisite corporate power and authority
to enter into this Agreement and to perform their obligations hereunder and to
consummate the transactions contemplated hereby and thereby, including but not
limited to the assignments and licenses in Article 7. The execution and delivery
of the Agreement and the consummation of the transactions contemplated hereby
have been duly authorized by all necessary corporate action on the part of
SELLERS, including any necessary action by shareholders. The Agreements have
been duly executed and delivered by SELLERS, and, assuming the valid execution
and delivery of the Agreements by NEOGEN, the Agreements constitute valid and
binding obligations of SELLERS, enforceable in accordance with their terms,
except as such enforcement may be limited by applicable bankruptcy, insolvency,
reorganization or other similar laws relating to or affecting the enforcement of
creditors' rights generally and by principles of equity regarding the
availability of remedies.

         4.3 Consents and Approvals. Except as disclosed on Schedule 8, the
execution, delivery and performance of this Agreement by SELLERS will not (a)
violate any provision of the Certificate of Incorporation or the Bylaws of any
of the SELLERS; (b) require any filing with, or permission, consent or approval
of, or the giving of any notice to, any U.S., state or local governmental agency
or instrumentality by SELLERS, or (c) violate any statute, ordinance, rule,
regulation, order or decree of any governmental agency or instrumentality
applicable to SELLERS or by which any of its properties or assets may be bound;
or (d) result in a violation or breach of, constitute (with or without the
giving of notice or lapse of time or both) a default, give rise to any right of
termination under, or result in the creation of any Lien, on the assets
transferred hereunder to NEOGEN; or (e) violate, with or without notice or the
passage of time, any contract or agreement relating to the Business to which any
of SELLERS is a party or to which any of the assets are bound.

         4.4 Litigation, Claims, Violations. As of the Closing Date, except as
disclosed in Schedule 8, there is no action, suit, proceeding or investigation
relating to the Business pending in any court or before any arbitrator or any
governmental agency or instrumentality or, to the knowledge of SELLERS,
threatened against SELLERS or the operation of the Business which could
materially affect the Acquired Assets. As of the Closing Date, SELLERS have not
received any written notice from the U.S. FDA or other governmental agency
concerning any violation of FDA or other governmental agency regulations in its
operation of the Business. SELLERS are not in default with respect to any order,
writ, injunction or decree of any court of federal, state, or municipal or other
governmental department, commission, board, agency or instrumentality, domestic
or foreign, and that, except for the injunction relating to the Kohne patents of
Gen-Probe Incorporated, there are

                                                                             -6-
<PAGE>

no such orders, decrees, injunctions or regulations issued specifically against
SELLERS which may affect, limit or control the method or manner of the Business,
the Acquired Assets or any transactions contemplated by this Agreement.

         4.5 Intellectual Property(e) . As of the Closing Date, SELLERS have the
unencumbered right to grant the licenses granted in Section 7.1. Except as
disclosed in Schedule 8, SELLERS are in compliance with and are not in default
under any of license agreement listed on Schedule 3, and to SELLERS' knowledge,
all other parties to any of such license agreements are in full compliance with
and are not in default under any of the license agreements.

         (1)      Schedule 9 (Patents, Copyrights and Trademarks Used in the
                  Business) sets forth a complete list of all patents,
                  trademarks, copyrights and service marks, owned (by assignment
                  or license) and used by SELLERS in the conduct of the Business
                  that are currently issued or registered in any jurisdiction.
                  SELLERS have good and marketable title to all patents,
                  trademarks, service marks and copyright assets listed on
                  Schedule 4 free and clear of all Liens (except for such
                  license agreements listed in Schedule 3) and all filing or
                  maintenance fees that are required to maintain such
                  registrations that are due and payable as of the date of this
                  Agreement have been paid and all associated maintenance
                  filings have been made.

         (2)      Schedule 4 sets forth a complete list of all software that the
                  SELLERS have had written or developed by any person or entity
                  not an employee of SELLERS for use solely in the conduct of
                  the Business, lists the current owner of the copyright
                  interest in such software, and if SELLERS are the current
                  owner, lists the date of the written assignment of the
                  copyright interest to SELLERS.

         (3)      SELLERS have not granted or committed to grant any
                  Intellectual Property rights of SELLERS in the Food Testing
                  Field of any nature whatsoever to any third party except as
                  disclosed in Schedule 8.

         (4)      Except as disclosed in Schedule 8, no claim has been asserted
                  in writing or orally to SELLERS by any person or entity (i) to
                  the effect that any action by SELLERS in the conduct of the
                  Business infringes on the Intellectual Property rights of any
                  other person or entity; or (ii) that challenges or questions
                  the right of SELLERS to use any Intellectual Property being
                  used by them in the conduct of the Business; or (iii) which
                  asserts any ownership right in SELLERS' Intellectual Property
                  being used by them in the conduct of the Business; or (iv)
                  which asserts the right of any third party to use without
                  license or permission of SELLERS any Intellectual Property.

         (5)      As of the Closing Date, except as disclosed in Schedule 8,
                  each of SELLERS has no knowledge that the sale of the products
                  listed on Schedule 2.1 -

                                                                             -7-
<PAGE>

                  Products of the Business - that are manufactured by SELLERS
                  infringes any U.S. patent issued on or before March 1, 2001.

         (6)      Except as disclosed in Schedule 8, each of SELLERS has no
                  knowledge of any person or entity infringing upon or of any
                  person or entity has misappropriated any of SELLERS'
                  Intellectual Property .

         (7)      Except as disclosed in Schedule 8, as of the Closing Date,
                  Schedule 3 lists all material licenses by which SELLERS
                  license from third parties any Intellectual Property rights
                  covering the GENE-TRAK products which are, as of the Closing
                  Date, manufactured and sold or planned for introduction in the
                  Food Testing Field by GENE-TRAK.

          4.6 Assigned Properties. SELLERS have good and marketable title to the
Acquired Assets, free and clear of all Liens. SELLERS have delivered to NEOGEN
true and complete copies of all written leases, contracts, agreements, options,
purchase orders, instruments and commitments relating solely to the Acquired
Assets or the Business. Except as set out in Schedule 8, all Contracts, Licenses
and Immunities Agreements, Service Agreements and Purchase Orders are legally
valid and binding and in full force and effect, and to SELLERS' knowledge, there
are no defaults or breaches by SELLERS or counterclaims or defenses against them
under the Contracts and Licenses and Immunities Agreements. SELLERS have
received no written notice of any default, breach, counterclaim or offset by any
other party to any of the Contracts, Licenses and Immunities Agreements, Service
Agreements and Purchase Orders, nor do SELLERS have any knowledge thereof. All
Contracts, Licenses and Immunities Agreements, Service Agreements and Purchase
Orders will continue in full force and effect on the same terms as currently
exists, notwithstanding the consummation of the sale contemplated by this
Agreement.

         4.7 Financial Information. SELLERS have provided in Schedule 10 the (i)
unaudited balance sheet and statements of income for the Business as of and for
the period ended December 31, 2000 ("Unaudited Financial Statements"); and (ii)
interim financial statements for the six month period ending June 30, 2001
("Interim Financial Statements") (collectively, "Financial Statements"). The
Financial Statements:

                  (1) Have been prepared in accordance with the books of account
         and records of SELLERS.

                  (2) Fairly present and are true, complete and correct
         statements of SELLERS' financial position in the Business and the
         results of their operations of the Business as of and for the periods
         specified in the Financial Statements.

                  (3) Have been prepared in accordance with generally accepted
         accounting principles ("GAAP") consistently applied.

                  (4) Do not include or omit to state any fact that renders them
         misleading.

                  (5) Make full and adequate disclosure of all SELLERS'
         obligations and liabilities (fixed or contingent, known or unknown).

                                                                             -8-
<PAGE>

                  (6) Do not contain any items of special or non-recurring
         income or expenses except as expressly stated in the Financial
         Statements.

         4.8 Receivables. The list of SELLERS' receivables ("Receivables")
attached as Schedule 11 is a complete and accurate list of all the Receivables.
All of the Receivables listed on Schedule 11 arose from bona fide sales
transactions of SELLERS, and no unreserved portion of the Receivables is subject
to counterclaim or offset or is otherwise in dispute. All of the Receivables are
good and collectible in full in the ordinary course of business at the net
aggregate amounts, less the reserve amount disclosed on Schedule 11.

         4.9 Inventories. The inventories reflected on the Financial Statements
and the Inventories are accurately and consistently valued at first in first out
standard cost method of accounting for inventories in accordance with GAAP
("Inventories"). The Inventories, in the aggregate, are usable and saleable in
the ordinary course of the Business within 75 days following the Closing. No
Inventories have been consigned to others.

         4.10 Contracts. Except as set out in Schedule 8, Schedules 2, 3, 4, 5
and 6 describe all written or oral licenses, contracts, purchase orders and
service agreements (except for such oral licenses, contracts, purchase orders
and service agreements that are terminable within ninety (90) days without any
financial penalty or that do not entail an annual commitment of greater than
$5,000) to which SELLERS are a party or to which it is bound and which solely
arose out of, or solely relate to, the Acquired Assets or the Business that
extend beyond the Closing Date. SELLERS have delivered true and correct copies
of all such documents evidencing the Contracts and Licenses and Immunities to
NEOGEN. If NEOGEN assumes such licenses, contracts, purchase orders and service
agreements, the benefits thereof may be assigned to NEOGEN and NEOGEN shall be
vested with SELLERS' rights thereunder notwithstanding the consummation of the
transactions contemplated by this Agreement, except as described on Schedule 8.

         4.11 Compliance with Law. SELLERS have complied with all applicable
laws, orders and regulations of any federal, state or municipal or other
governmental department, commission, board, agency or instrumentality, domestic
or foreign, having jurisdiction, including, but not limited to, laws, orders and
regulations thereof relating to antitrust, wage, hours, collective bargaining,
environmental protection, employee safety, or legislation pertaining to illegal
bribes or kickbacks.

          4.12 No Adverse Changes. Since January 1, 2001, except as disclosed in
Interim Financial Statements, there has been no material adverse change in the
condition, financial or otherwise, of the SELLERS or the Acquired Assets or in
the Business other than changes (not in the aggregate either material or
adverse) occurring in the ordinary course of business.

         4.13 Warranties and Product Liability. SELLERS have previously
delivered to NEOGEN true, correct and complete copies of all outstanding
standard product warranties and guaranties given by SELLERS with respect to the
Business and true, correct and compete copies of all other product warranties
and guaranties now in effect with respect to products manufactured or sold by
SELLERS concerning the Business. Except as fully described in Schedule 8, there
are no pending claims or actions against the SELLERS for breach of warranty or
based upon product liability (whether based on tort or contract principles) and,
to the best of SELLERS' knowledge, no such claims or actions are threatened.
There are no defects in craftsmanship, design or engineering

                                                                             -9-
<PAGE>

with respect to any product now or previously sold or manufactured by SELLERS in
the Business which may constitute the basis for any such claim against SELLERS
or NEOGEN. All of SELLERS' products being sold to NEOGEN as part of the Acquired
Assets are listed in attached Schedule 2.1. SELLERS represent that these are all
of the products within the Food Testing Field.

         4.14 Contingent and Undisclosed Liabilities. There are no debts,
obligations or liabilities, of any nature whatsoever, relating to the Business
or the Acquired Assets not disclosed in writing to NEOGEN and SELLERS know of no
basis for any assertion of any claim against SELLERS for any liability relating
to the Business or Acquired Assets except those disclosed in Schedule 8.

         4.15 Performance of Contracts. Except as disclosed in Schedule 8,
SELLERS are not in default, nor have they breached any provision of, any
contract, agreement, or license listed on Schedules 3 and 4. Except as disclosed
in Schedule 8, SELLERS have fully performed each material term, condition and
covenant of each such contract, agreement, lease, obligation, license or permit
required to be performed on or prior to the date of this Agreement. Except as
disclosed in Schedule 8, SELLERS know of no state of facts which, with or
without the giving of notice or the passage of time, or both, would give rise to
any default or revocation under any contract, agreement or license listed on
Schedules 2, 3, 4, 5 and 6. Except as disclosed in Schedule 8, SELLERS are
neither subject to any penalty, discount or liquidated damages due to the
delayed delivery of products, goods or services of the Business, nor has it
received any written notice that any of the Business's customer relations are in
jeopardy because of such late deliveries or otherwise.

         4.16 Customer Relations. SELLERS know of no state of facts, nor have
any written communications been made to it, which would indicate that (i) any
current customer of SELLERS which accounted for more than 5% of SELLERS' sales
relative to the Business for the most recent fiscal year ending, or (ii) any
current supplier of SELLERS (if such supplier could not be replaced by SELLERS
at comparable cost), will terminate its business relations with SELLERS.

         4.17 Accounting Books and Records. The books and accounts of SELLERS
relating to the Business are true, complete and correct in all material respects
and fully and fairly reflect all of the transactions entered into by or on
behalf of SELLERS to which they are a party.

         4.18 Employee Relations. (a) Schedule 12 sets forth a list of all of
the officers, employees and agents of Vysis, Inc. that are employed full-time in
the Business and, for each individual, indicates his or her position, salary or
wage rate and respective fringe benefits and any other remuneration paid or
payable. Upon termination of the employment of any of the SELLERS' employees by
SELLERS, NEOGEN shall not incur any liability for severance or termination pay
or any other obligation to SELLERS' employees..

         (b) With respect to all of its employees, former employees and
qualified beneficiaries as of the Closing Date, SELLERS have or will comply with
all applicable health care continuation requirements under the Code, ERISA and
current and proposed Federal Regulations. Accordingly, SELLERS will be
responsible for providing continuation coverage to any employees of SELLERS that
elect continuation coverage. SELLERS represent that NEOGEN will not be
responsible for providing continuation coverage to any of SELLERS' employees.
SELLERS agree to provide NEOGEN, promptly after written request, with all
information that it deems necessary to determine

                                                                            -10-
<PAGE>

whether there have been any failures to comply with the continuation health care
requirements of section 162(k)/4980B of the Code and sections 601 through 609 of
ERISA as such requirements have applied to any group health plan maintained by
or for which failure occurred with respect to any current or former employee of
or any spouse, former spouse, dependent child, or former dependent child of any
such employee, on or prior to the Closing Date. SELLERS further agree to provide
to NEOGEN, promptly after written request, all information that it deems
necessary to correct any failures to comply with such continuation health care
coverage requirements. Such information shall include, without limitation, the
identification of all covered employees (as defined in section
162(k)(7)(B)/4980B(f)(7) of the Code) and their qualified beneficiaries (as
defined in section 162(k)(7)(B)/4980B(g)(1) of the Code), the identification of
all qualifying events with respect to such covered employees or qualified
beneficiaries (as defined in section 162(k)(3)/4980B(f)(3) of the Code, and
information otherwise demonstrating compliance with all of the continuation
health care coverage requirements of section 162(k)/4980B of the Code and
sections 601 through 608 of ERISA. For purposes of this provision, references to
the Code and ERISA shall include references to any provisions of such statutes
as they may be amended from time to time.

         (c) Schedule 13 sets forth all "employee welfare benefit plans",
"employee pension benefit plans" and "multi-employer plans" within the
respective meanings of Sections 3(1) and 3(2) and 3(37) of the Employment
Retirement Income Security Act of 1974, as amended ("ERISA"), all incentive
compensation plans, benefit plans for retired employees and all other employee
benefit plans maintained by SELLERS, or to which SELLERS have made payments or
contributions on behalf of its employees since 1974, including, without
limitation, all plans or contracts providing for bonuses, pensions,
profit-sharing, stock options, stock purchase rights, deferred compensation,
insurance and retirement benefits of any nature, whether formal or informal and
whether legally binding or not (each such plan is referred to individually as a
"Plan", collectively as the Plans").

         4.19 [Intentionally Left Blank]

         4.20 Environmental Matters. Except as disclosed on Schedule 8:

         (1)      SELLERS' Hopkinton, Massachusetts facility (the "Premises")
                  and the operations at that facility comply with all applicable
                  Environmental Laws.

         (2)      SELLERS have not received any written notice from the United
                  States Environmental Protection Agency or any other
                  Governmental Authority claiming that (i) the Hopkinton
                  facility or any use thereof violates any of the Environmental
                  Laws, or (ii) SELLERS or any of their employees or agents have
                  violated any of the Environmental Laws in the operations at
                  Hopkinton.

         (3)      SELLERS have not incurred any liability to the States of
                  Illinois or Massachusetts, the United States of America or any
                  other Governmental Authority under any of the Environmental
                  Laws.

         (4)      There are no Environmental Enforcement Actions pending or, to
                  the best of SELLERS' knowledge, threatened.

                                                                            -11-
<PAGE>

                  (A)      The following definitions apply to this paragraph.
                           "Environmental Claim" shall mean any investigation,
                           notice, violation, demand, allegation, action, suit,
                           injunction, judgment, order, consent decree, penalty,
                           fine, lien, proceeding, or claim (whether
                           administrative, judicial, or private in nature)
                           arising (A) pursuant to, or in connection with, an
                           actual or alleged violation of, any Environmental
                           Laws, (B) in connection with any Hazardous
                           Substances, (C) from any abatement, removal,
                           remedial, corrective, or other response action in
                           connection with Hazardous Substances, Environmental
                           Laws or other order of a Governmental Authority or
                           (D) from any actual alleged damage, injury, threat,
                           or harm to health, safety, natural resources, or the
                           environment.

                  (B)      "Environmental Enforcement Actions" means actions or
                           orders instituted, threatened, required or completed
                           by any Governmental Authority and all claims made or
                           threatened by any person against SELLERS with respect
                           to the Premises arising out of or in connection with
                           any of the Environmental Laws or the assessment,
                           monitoring, clean-up, containment, re-mediation or
                           removal of, or damages caused or alleged to be caused
                           by, any Hazardous Substances (A) located on or under
                           the Premises, (B) emanating from the Premises or (C)
                           generated, stored, transported, utilized, disposed
                           of, managed or released by SELLERS on, under or from
                           the Premises.

                  (C)      "Environmental Laws" means federal, state and local
                           laws, statutes, ordinances, rules, regulations,
                           codes, orders, judgments, orders and the like
                           applicable to (A) environmental conditions on, under
                           or emanating from the Premises including, but not
                           limited to, (a) laws of the States of Illinois and
                           Massachusetts; and the associated rules and
                           regulations promulgated in connection with any of
                           these laws, and (b) laws of the federal government
                           commonly known as CERCLA, RCRA, the Toxic Substance
                           Control Act, as amended, the Federal Water Pollution
                           Control Act, as amended, and the Federal Clean Air
                           Act; and the associated rules and regulations
                           promulgated in connection with any of these laws; and
                           (B) the generation, storage, transportation,
                           utilization, disposal, management or release of
                           Hazardous Substances by SELLERS (whether or not on,
                           under or from the Premises) or SELLERS (on, under or
                           from the Premises).

                  (D)      "Governmental Authority" means agencies, authorities,
                           bodies, boards, commissions, courts,
                           instrumentalities, legislatures and offices of any
                           nature whatsoever for any government unit or
                           political subdivision, whether federal, state,
                           county, district, municipal, city or otherwise, and
                           whether now or later in existence.

                  (E)      "CERCLA" shall mean the Comprehensive Environmental
                           Response Compensation, and Liability Act of 1980, as
                           amended by the

                                                                            -12-
<PAGE>

                           Superfund Amendments and Reauthorizations Act of
                           1986, 42 USC 9601 et seq., and future amendments.

                  (F)      ""Hazardous Substances" shall mean, collectively, (A)
                           any "hazardous material," "hazardous substance,"
                           "hazardous waste," "oil," "regulated substance,"
                           "toxic substance," "restricted hazardous waste,"
                           "special waste" or words of similar import as defined
                           under any of the Environmental Laws; (B) asbestos in
                           any form; (C) urea formaldehyde foam insulation; (D)
                           polychlorinated biphenyls; (E) radon gas; (F)
                           flammable explosives; (G) radioactive materials; (H)
                           any chemical, contaminant, solvent, material,
                           pollutant or substance that may be dangerous or
                           detrimental to the environment or the health and
                           safety of occupants of the Premises or of the owners
                           or occupants of any other real property nearby the
                           Premises, and (I) any substance, the generation,
                           storage, transportation, utilization, disposal,
                           management, Release or location of which on, under or
                           from the Premises is prohibited or otherwise
                           regulated pursuant to any of the Environmental Laws.

                  (G)      "RCRA" shall mean the Solid Waste Disposal Act, as
                           amended by the Resource Conservation and Recovery Act
                           of 1976 and Hazardous and Solid Waste Amendments of
                           1984, 42 USC 6901 et seq., and any future amendments.

                  (H)      "Release" shall mean any spilling, leaking, pumping,
                           pouring, emitting, discharging, injecting, escaping,
                           leaching, dumping or disposing into the indoor or
                           outdoor environment, including without limitation the
                           abandonment or discarding of barrels, drums,
                           containers, tanks, and other receptacles containing
                           or previously containing any Hazardous Substances.

         4.21 Permits and Licenses. The attached Schedule 14 is a complete and
accurate list of all licenses, permits, authorizations and approvals required by
any Governmental Entities (collectively, "Permits"), other than non-operational,
corporate or qualification to do business Permits, currently held by SELLERS to
own, lease and operate the Business. All of the Licenses are valid and in full
force and in effect. Except as disclosed in Schedule 8, SELLERS are in full
compliance with all obligations under all Permits, and no event has occurred
that allows, or after notice or lapse of time would allow, revocation or
termination of any Licenses. The term "Governmental Entities" shall mean any
federal, state, local, foreign or supranational court, commission, governmental
body, regulatory agency, authority or tribunal.

         4.22 Representations and Warranties True and Correct. The
representations and warranties contained herein, and all statements or
information disclosed by any of the Exhibits, do not include any untrue
statement of a material fact nor omit to state a material fact required to be

                                                                            -13-
<PAGE>

stated herein or therein or necessary in order to make the statements herein or
therein, in light of the circumstances under which they are made, not
misleading.

ARTICLE 5 REPRESENTATIONS AND WARRANTIES OF NEOGEN

         NEOGEN represents and warrants to SELLERS the following:

         5.1 Organization, Standing and Power. NEOGEN is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Michigan. NEOGEN has the corporate power to own its properties and to carry on
its business as now being conducted.

         5.2 Authority. NEOGEN has all requisite corporate power and authority
to enter into this Agreement and to perform its obligations hereunder and
thereunder and to consummate the transactions contemplated hereby and thereby.
The execution and delivery of the Agreement and the consummation of the
transactions contemplated hereby have been duly authorized by all necessary
corporate action on the part of NEOGEN. The Agreement has been duly executed and
delivered by NEOGEN, and, assuming the valid execution and delivery of this
Agreement by SELLERS, the Agreements constitute valid and binding obligations of
NEOGEN, enforceable in accordance with their terms except as such enforcement
may be limited by applicable bankruptcy, insolvency, reorganization or other
similar laws relating to or affecting the enforcement of creditors' rights
generally and by principles of equity regarding the availability of remedies.

         5.3 Consents and Approvals. The execution, delivery and performance of
this Agreement by NEOGEN will not (a) violate any provision of the Articles of
Incorporation or the Bylaws of NEOGEN; (b) require any filing with, or
permission, consent or approval of, or the giving of any notice to, any U.S.
governmental entity by NEOGEN; (c) violate any statute, ordinance, rule,
regulation, order or decree of any governmental entity applicable to NEOGEN or
by which any of its properties or assets may be bound; or (d) result in a
violation or breach of, constitute (with or without the giving of notice or
lapse of time or both) a default, give rise to any right of termination under,
or result in the creation of any Lien upon NEOGEN or any of its property that
would materially interfere with NEOGEN's performance of its obligations
hereunder.

                                                                            -14-
<PAGE>

ARTICLE 6 BUSINESS TRANSFER

         6.1 Orders/Technical Service Support. After the Closing Date, SELLERS
shall use their best efforts to ensure that all communication from third parties
related exclusively or primarily to the Business will be forwarded immediately
to NEOGEN, and will transfer immediately to NEOGEN all orders for the GENE-TRAK
products that are received after the Closing Date. SELLERS will provide
reasonable amounts of training support to NEOGEN to assist its takeover of the
order entry support for the Business.

         6.2 Sales Transition. Promptly after the Closing Date, VYSIS shall post
a notice acceptable to NEOGEN of the transfer of the Business to NEOGEN in its
Web Site.

         6.3 Operations at Hopkinton. SELLERS agree to carry out GENE-TRAK's
Business activities as directed and controlled by NEOGEN at the Hopkinton site
from the Closing Date until October 31, 2001. These activities will include
product manufacture and shipment, raw materials delivery, and customer
communications. NEOGEN acknowledges that in its performance of the obligations
under this Section 6.3, that SELLERS are not obligated to hire any additional
employees or consultants or to replace any employees presently working at
Hopkinton. From the Closing Date through August 31, 2001, SELLERS will provide
NEOGEN at the Hopkinton facility with training in the technical support for the
Business. SELLERS make no representation or warranty concerning the post-Closing
Date activities by SELLERS at NEOGEN's direction and control. NEOGEN assumes
full responsibility and liability for the activities of SELLERS at the direction
of NEOGEN; provided that NEOGEN assumes no responsibility for (i) any
Environmental Claim arising from the activities at Hopkinton after the Closing
Date or (ii) any uninsured workers compensation costs.

         6.4 Management Information Systems Support. SELLERS and NEOGEN will
cooperate in the transfer to NEOGEN of administrative, accounting and data
processing support ("MIS Support") presently provided by VYSIS to GENE-TRAK.
NEOGEN acknowledges that no rights or title to any MIS Support software used by
VYSIS is being transferred to NEOGEN hereunder. NEOGEN will use its best efforts
to complete the transfer of MIS Support by September 30, 2001. From the Closing
Date through October 31, 2001, VYSIS will provide NEOGEN with access to its
Avante business financial data system for purposes of transfer to NEOGEN of data
related solely to the Business contained in Avante.

         6.5 Transition Costs. NEOGEN will reimburse VYSIS for the actual costs
of payroll , including benefit charges of 18% of payroll costs, for the
employees at Hopkinton, accounting support and MIS support charges not to exceed
$2,000 each, actual facility costs (exclusive of all obligations, other than
utilities, pursuant to the Hopkinton real estate lease) and any raw material,
purchasing and other expenses approved by NEOGEN in advance, incurred by VYSIS
after the Closing Date in the transition of the business to NEOGEN.

                                                                            -15-
<PAGE>

ARTICLE 7 LICENSE COVENANTS

         7.1 License Grant.

         (a) Subject to the terms and conditions in this Agreement, SELLERS
hereby grant to NEOGEN, and NEOGEN hereby accepts, a worldwide, exclusive,
paid-up, irrevocable, transferable license, with right to sublicense, to use in
any matter in the Food Testing Field (i) all GENE-TRAK unpatented business and
technical information including but not limited to product formulations,
manufacturing processes and probe sequences, and (ii) all of SELLERS' unpatented
business and technical information that relates to both the Business and to
SELLERS' other business activities, and to use in any manner GENE-TRAK
unpatented business and technical information to detect organisms by detecting
or quantifying nucleic acids of any and all materials associated with the
production or processing of foodstuffs or beverages (including but not limited
to water and milk) intended for human or animal consumption in any or all phases
of production. NEOGEN acknowledges that none of SELLERS' unpatented business and
technical information relating to its Cellular Genomics and Genomic Microarray
businesses shall be deemed information that relates to both the Business and to
SELLERS' other business activities. The grant of this exclusive license is also
subject to SELLERS' retained right to use the licensed business and technical
information in all other fields and to use business information for financial
record keeping, claims handling, securities law obligations, financial
reporting, tax purposes and litigation.

         (b) At the Closing, NEOGEN and SELLERS will enter into Exhibits B
(Assignment of Immunity from Suit under Gen-Probe's Kohne Patents), C
(Assignment of Orion and Institut Pasteur Licenses) and D (Assignment of the
Gene-Trak Licenses) transferring to NEOGEN certain immunities from suit and
licenses used in the conduct of the Business.

         7.2 Limitations.

         (a) The licenses granted from SELLERS to NEOGEN in Section 7.1 are
limited to the rights expressly granted therein and do not include: (i) any
license of any technical information relating to any human clinical, human
clinical research or human research product, assay or testing service, (ii) a
license to any Patent Right for any human clinical, human clinical research or
human research product, assay or research service, or (iii) a license to any
other of SELLERS Intellectual Property Rights not expressly licensed to NEOGEN
hereunder.

         (b) This Agreement shall not be construed as creating any restriction
upon SELLERS' research, development, clinical trials, marketing, sale and
collaborative efforts for any product, assay or service in any field outside the
Food Testing Field nor for either party in any animal or plant genomic-based
research testing of food animals or plants.

         7.3 Notice of Exercise of Gen-Probe Option. SELLERS agree to notify
NEOGEN within thirty (30) days after it issues a license under the Option
Agreement granted Gen-Probe of the name and address of the licensee.

         7.4 Non-Disclosure of Gen-Probe Option Terms. Except as necessary to
comply with any securities law reporting obligations, SELLERS agree not to
disclose the terms of its Option Agreement with Gen-Probe.

                                                                            -16-
<PAGE>

         7.5 Non-Amendment of Licenses. SELLERS agree they will not enter into
any amendment of the Orion, Institut Pasteur, or the Regents of the University
of California Stanbridge Licenses, nor of the Immunity from Suit under the Kohne
Patents of Gen-Probe, where such amendment adversely impacts NEOGEN's rights in
the Food Testing Field.

         7.6 Application of General Provisions to Exhibits. SELLERS and NEOGEN
agree that the provisions of Article 10 and of Paragraphs 9.2, 9.3, 9.4, 11.1,
11.3, 11.4, 11.5, 11.6, 11.9, 11.10, 11.14 ,11.16 and 11.17 of this Agreement
shall be applicable to the executed agreements identified in Exhibits B, C and
D.

         7.7 Cepheid Joint Product Development and Distribution Agreement.
SELLERS and NEGOEN acknowledge that VYSIS entered into a Joint Product
Development and Distribution Agreement with Cepheid ("Cepheid") as of November
31, 1998 ("CA"), a copy of which NEOGEN acknowledges receiving. Without
limitation of NEOGEN'S other rights under this Agreement: (i) VYSIS shall, after
the Closing, use reasonable efforts to (A) obtain Cepheid's consent to the
assignment of the CA to NEOGEN of VYSIS' rights and obligations to the extent of
the food testing field ("Consent"); (ii) after the Closing, NEOGEN and VYSIS
will cooperate with each other in any reasonable and lawful arrangement designed
to provide such benefits to NEOGEN (including, if requested by NEOGEN, any
reasonable arrangement with respect to an agreement with Cepheid for which
agreement NEOGEN is unable to obtain a consent and under which arrangement VYSIS
perform those duties at the expense and request of and receive those benefits on
behalf of NEOGEN). To the extent that NEOGEN is provided the benefits pursuant
to this provision of the CA, NEOGEN shall perform the obligations of VYSIS with
respect to periods following the Closing, but only to the extent that such
action by NEOGEN would not result in any violation of any applicable law or
default under the CA; and (iii) after the Closing, VYSIS shall not amend the CA
in any way that will adversely affect NEOGEN without first obtaining its prior
written approval. NEOGEN and VYSIS agree that NEOGEN will have to negotiate
compensation, license fees and running royalty, to VYSIS for the licenses under
the Barcode technology (as defined in the CA). The parties agree to determine
VYSIS' compensation for these items pursuant to the applicable terms of the CA.
The parties agree that the purpose of this provision is to enable NEOGEN to
obtain VYSIS' rights and obligations pursuant to the CA limited to the food
testing field.

ARTICLE 8 CONTRACT ASSIGNMENT AND EMPLOYMENT MATTERS

         8.1 Contracts, Licenses and Immunities Agreements and Service
Contracts. SELLERS hereby assign to NEOGEN all its right and interest in and to
all Contracts, Licenses and Immunities Agreements, Service Agreements and
Purchase Orders listed on Schedules 2, 3, 4,5 and 6, respectively. NEOGEN and
SELLERS shall cooperate in notifying the other party to such Contracts, Licenses
and Immunities Agreements, Service Contracts and Purchase Orders and to secure
any consents necessary to effectuate the assignment. Assumption of Contract
Obligations.

         (a) NEOGEN hereby assumes all SELLERS' obligations listed on attached
Schedule 2.2 to be performed after the Closing Date

                                                                            -17-
<PAGE>

         (b) NEOGEN assumes no warranty obligations (i) relating to the sale or
service of products by SELLERS prior to the Closing Date, or (ii) arising out of
the sale of the Inventory that NEOGEN is buying as part of this Agreement.

         8.2 Employment. In order to facilitate a smooth transfer of the
Business and to further the purposes of this Section 8.2 and this Agreement,
SELLERS shall use their best efforts to encourage and promote the acceptance of
any offers made by NEOGEN to VYSIS employees pursuant to this Agreement. In
connection with the transfer of the Business, NEOGEN shall have the right to
solicit the employees of VYSIS who are identified on Schedule 12. NEOGEN agrees
to consider such employees for employment and to make any offers of employment
before the Closing Date. SELLERS agree that the employees listed on Schedule 12
may be employed by and provide services to NEOGEN; provided, that SELLERS will
continue to enforce the proprietary, confidentiality and similar provisions in
any agreements with such employees to the extent such enforcement relates to
information not used in the Business as of the Closing Date. The human resources
departments of the parties will cooperate in the hiring of any such employee by
NEOGEN. The hiring of employees of VYSIS shall be at the sole discretion of
NEOGEN, and NEOGEN shall have no obligation to make offers of employment to any
person. As between the parties, all rights to accrued vacation, to any severance
payments and to all other rights of employees of VYSIS created upon the
termination of their employment with VYSIS shall remain the sole responsibility
of SELLERS.

         8.3 SELLERS represent that all current employee agreements for
employees assigned full-time to the Business and confidentiality agreements
solely related to the Business entered into since January 1, 1999, are included
in Schedule 2. SELLERS agree that upon the future written request of NEOGEN,
that it will assign to NEOGEN any employee agreements for former employees of
the Business and confidentiality agreements solely relating to the Business that
still have outstanding confidentiality or non-use obligations, as necessary for
NEOGEN to protect the the Business.

ARTICLE 9 GENERAL COVENANTS

         9.1 Access and Rights of Inspection. In addition to the access rights
under Article 6, for ninety (90) days after the Closing Date, SELLERS will allow
NEOGEN and its counsel, accountants, consultants and other representatives
reasonable access, during normal business hours and so as not to unreasonably
interfere with the business operations of SELLERS, to all properties, Contracts,
books and records, including technical service records used in or relating to
SELLERS' operation of the Business.

         9.2 Further Assurances. Both before and after the Closing, each party
hereto agrees to execute, acknowledge and deliver such further instruments and
to do all such other acts as may be necessary or appropriate in order to carry
out the purposes and intents of this Agreement. Without limiting the foregoing,
SELLERS agree that it will, both prior to and after the Closing, without
demanding or receiving any further consideration, at the request of NEOGEN,
perform any and all legal acts, including the execution and acknowledgment of
instruments, that may be or become necessary or convenient for effectuating the
assignment of any property assigned hereunder.

                                                                            -18-
<PAGE>

         9.3 Claims Handling. SELLERS and NEOGEN each agree to maintain records
related to the Business in accordance with their normal information storage
policies. In addition to the access rights under Article 6 and Section 9.1,
SELLERS and NEOGEN agree to cooperate concerning the handling of any claims,
tax, government reporting, government investigation or litigation matters
arising after the Closing Date and relating to the Business. In addition to the
access rights under Article 6 and Section 9.1, NEOGEN and SELLERS agree to
provide the other access during normal business hours and upon reasonable
advance notice to any documents in their possession relating to the Business for
purposes of handling of any claims, tax, government reporting, government
investigation or litigation matters relating to the Business arising after the
Closing Date.

         9.4 Confidentiality Regarding Information of Business.

         (a) SELLERS agree that, after the Closing, they shall not use nor
disclose to any person or entity not employed by, or not engaged to render
services to, SELLERS, any non-public trade secrets, financial data, operational
methods, customer lists, marketing and sales information or other proprietary
information relating to the Business, except (i) in conjunction with the
operation of its retained businesses, and then under the conditions used by
SELLERS to protect its own business information and (ii) except for purposes of
SEC filings. SELLERS shall have the right to make any filing with any
governmental agency as necessary in SELLERS' judgment to comply with any
securities or other applicable law, including the filing of financial statements
containing financial information of the Business, and to issue any press release
concerning SELLERS' retained businesses that may incorporate financial and
operating performance information of the Business. The obligations in this
Section 9.4 (a) shall not apply to any information that (i) becomes part of the
public domain through no fault of SELLERS, or (ii) is disclosed to SELLERS by a
third party not under an obligation of confidence to NEOGEN.

         (b) NEOGEN agrees that, after the Closing, it shall not use nor
disclose to any person or entity not employed by, or not engaged to render
services to, NEOGEN, any non-public trade secrets, financial data, operational
methods, customer lists, marketing and sales information or other proprietary
information relating to SELLERS' retained business, except (i) in conjunction
with the operation of the Business under the conditions used by NEOGEN to
protect its own business information and (ii) except for purposes of SEC
filings. NEOGEN shall have the right to make any filing with any governmental
agency as necessary in NEOGEN's judgment to comply with any securities or other
applicable law, including the filing of financial statements containing
financial information of the Business. The obligations in this Section 9.4 (b)
shall not apply to any information that (i) becomes part of the public domain
through no fault of NEOGEN, or (ii) is disclosed to NEOGEN by a third party not
under an obligation of confidence to any of SELLERS.

         9.5 Covenant Not to Compete.

         (a) In connection with the transfer of the Business to NEOGEN, for the
period from the Closing Date until the fifth anniversary of the Closing Date,
SELLERS will not compete with NEOGEN anywhere in the world in the marketing and
sale of products, assays and services in the Food Testing Field; provided that
(i) SELLERS' marketing and sale of any products,

                                                                            -19-
<PAGE>

assays and services in any field outside the Food Testing Field, including
without limitation thereto in the fields of human research, plant research and
animal research, human clinical research and human clinical use, shall be
permitted on a worldwide basis and not construed as violating this Section 9.5,
and (ii) SELLERS' licensing of any patent rights in any field of use, other than
licensing to any third parties (except for any licenses issued in the Food
Testing Field pursuant to Gen-Probe Obligations as defined in Exhibit D) in the
Food Testing Field of any patent rights licensed exclusively to NEOGEN, shall be
permitted on a worldwide basis and not construed as violating this Section 9.5,
and (iii) in the event of a purchase of SELLERS by an entity having existing
operations in the Food Testing Field before the date of such purchase of SELLERS
("ENTITY"), the continued performance by the ENTITY of its operations in the
Food Testing Field shall not be construed as violating this Section 9.5,
provided that the ENTITY's last annual total product revenues in the Food
Testing Field shall not exceed 10% of the ENTITY's last annual total revenues.

         (b) NEOGEN acknowledges that this non-compete covenant shall not be
construed as violated by any research and development activities outside of the
Food Testing Field of SELLERS, either performed internally or with third party
collaborators. Section 9.5 shall not preclude SELLERS from holding, as a passive
investment, not more than five percent (5%) of any class of securities, which
class is publicly traded on a U.S. securities exchange or the NASDAQ National
Market, of any corporation, partnership, business or other entity with
operations directly competitive with NEOGEN.

         9.6 Change of Corporate Names. SELLERS agree promptly after the Closing
Date to take the necessary corporate action and to file with the State of
Delaware the necessary documentation changing the names of Gene-Trak, Inc. and
Gene-Trak Systems Industrial Diagnostic Corporation to other names not using
Gene-Trak. SELLERS will deliver copies of the Delaware state filings to NEOGEN.

         9.7 Relief. SELLERS agree that the restrictive covenants in Paragraphs
9.4 and 9.5 are reasonable in their geographic scope and duration and may be
enforced by specific performance or otherwise. SELLERS and NEOGEN shall not
raise any issue of reasonableness as a defense in any proceeding to enforce any
of such covenants. In the event that, notwithstanding the foregoing, a covenant
included in Paragraph 9.4 and 9.5 of this Agreement shall be deemed by any court
to be unreasonably broad or violative of applicable law in any respect, it shall
be modified in order that it be reasonable or not violative of applicable law,
as the case may be, and shall be enforced accordingly. Without limitation of the
foregoing, in the event that, notwithstanding the foregoing, in any judicial
proceeding, a court shall refuse to enforce any of the covenants contained in
Paragraph 9.4 or 9.5 or any of the separate covenants deemed included in
Paragraph 9.4 or 9.5, then the unenforceable covenant shall be deemed eliminated
from the provisions of this Agreement for the purpose of those proceedings to
the extent necessary to permit such covenant and the remaining separate
covenants of Paragraph 9.4 or 9.5 to be enforced.

         9.8 Non-Amendment of Employment Agreements. SELLERS agree they will not
enter into any amendment of the Employment Agreements listed on Schedule 2.

         9.9 Release of American National Bank Lien. SELLERS represent and
warrant that the lien of American National Bank (ANB) against all of the assets
of SELLERS relates to a line of

                                                                            -20-
<PAGE>

credit under which SELLERS have taken no funds. SELLERS agree promptly after the
Closing Date to obtain a termination of the ANB lien and any other lien against
any of the Acquired Assets.

ARTICLE 10 SURVIVAL OF REPRESENTATIONS AND WARRANTIES; INDEMNIFICATION

         10.1 Survival of Representations and Indemnification. NEOGEN and
SELLERS agree that all representations, warranties and covenants of
SELLLERS("Representations"), except for Representations under Paragraphs 4.1,
4.2, 4.4, 4.5, 4.6, 4.10, 4.11, 4.13, 4.14, 4.15, 4.18 (b) and (c),, 4.20 and
4.22 (collectively, "Second Tier Reps"), shall survive the execution and
delivery of this Agreement and the Closing Date until July 31, 2003 ("First Tier
Reps"). Any claim for indemnification hereunder, except for claims (i) based on
fraud or intentional non-disclosure by SELLERS or (ii) based on breach of the
Second Tier Reps, must be made on or prior to July 31, 2003. Any claim for
indemnification of the First Tier Reps not noticed by July 31, 2003, shall be
irrevocably waived and released. Paragraphs 4.5 (2) - (7), 4.10, 4.13 and 4.14
of the Second Tier Reps shall survive the execution and delivery of this
Agreement and the Closing Date until July 31, 2006. Any claim for
indemnification with respect to the Representations listed in the preceding
sentence not noticed by July 31, 2006, shall be irrevocably waived and released.
Paragraphs 4.1, 4.2, 4.4, 4.5 (1), 4.6, 4.11, 4.15, 4.18 (b) and (c), 4.20 and
4.22 to the extent that it relates to one of the preceding items shall survive
the execution and delivery of this Agreement and the Closing Date until 6 months
after the expiration of the applicable statute of limitations.

         10.2 Indemnification by SELLERS. Subject to the limitations set forth
in Paragraph 10.6, SELLERS, jointly and severally, agree to indemnify and hold
NEOGEN harmless from and against any and all Damages (as defined in Paragraph
10.4) incurred by NEOGEN at any time arising out of:

         (1)      The inaccuracy or breach of any of the Representations made by
                  SELLERS in or pursuant to this Agreement;

         (2)      Any failure by SELLERS to perform any obligation or comply
                  with any covenant or agreement of SELLERS specified in this
                  Agreement or in any other document executed at Closing;

         (3)      Any claim (i) for wages or fringe benefits made by any
                  employee of SELLERS with respect to the period ending
                  immediately preceding the Closing Date; (ii) for severance
                  payments or other liabilities with respect to the termination
                  of any employees of SELLERS; or (iii) with respect to the
                  injury or death of any such employee arising out of events
                  occurring prior to the Closing Date;

         (4)      Any claim (including, without limitation, claims alleging
                  death or injury to persons or damage to property), whether
                  based in tort, contract or otherwise

                                                                            -21-
<PAGE>

                  resulting from or caused by any product sold, or service
                  provided, by SELLERS prior to the Closing Date;

         (5)      Any debt, obligation or liability, whether known or unknown,
                  fixed or contingent, of any nature whatsoever to the extent
                  based on SELLERS' activities before the Closing Date,
                  including but not limited to all environmental liabilities of
                  any nature (collectively, "Pre-Closing Debts"), other than any
                  Pre-Closing Debts which are part of the Assumed Liabilities;
                  or

         (6)      NEOGEN being deemed to be a "successor" employer to SELLERS
                  for the purpose of COBRA obligations; or

         (7)      The ownership, lease, use, occupation or operation of any
                  facility or property at any time owned, leased, used, occupied
                  or operated by Sellers, except for those matters specified in
                  Paragraph 6.3; or

         (8)      Any claims related to the EXCLUDED AGREEMENTS, EXCLUDED
                  PATENTS, EXCLUDED TRADEMARKS, EXCLUDED COPYRIGHTS and the
                  Discrimination Claim disclosed on Schedule 8.

         SELLERS specifically acknowledge and agree that NEOGEN may proceed
against any of SELLERS under Paragraph 10.2 without contemporaneously, or at any
time, proceeding against any other of them. Each of SELLERS agrees that it shall
not have any claim or right of indemnification or contribution or any other
right of recourse against any other Seller with respect to Damages and each of
SELLERS waives and releases any and all such claims and right, until all
indemnity obligations of SELLERS in favor of NEOGEN have expired.

         10.3 Indemnification by NEOGEN. NEOGEN agrees to defend, indemnify and
hold harmless SELLERS from and against any Damages incurred by reason of (i) any
breach of any representation, warranty or covenant of NEOGEN, (ii) any
liabilities arising from the operation or conduct of the Business by NEOGEN
subsequent to the Closing Date, (iii) any product shipped or manufactured by or
any services provided by the NEOGEN with respect to the Business subsequent to
the Closing Date, and (iv) SELLERS' activities as directed by NEOGEN under
Paragraph 6.3, except for any matters excluded in Paragraph 6.3.

         10.4 Damages. An Indemnified Party shall be entitled to recover the
full amount of any liabilities, losses, debts, obligations, monetary damages,
fines, fees, penalties, deficiencies, expenses (including amounts paid in
settlement, interest obligations, court costs, the reasonable costs of
investigators, the reasonable fees and expenses of attorneys, accountants,
financial advisors or other experts, and other reasonable expenses of litigation
or administrative proceedings) incurred due to the matter for which
indemnification is sought, but any recovery shall be net of any economic benefit
to which the Indemnified Party is entitled due to such liabilities, expenses,
costs or loss, including, without limitation, (i) any tax refund, reduction or
benefit, (ii) any insurance proceeds to which the Indemnified Party is entitled
and (iii) any warranty reimbursements (collectively, "Damages").10.5 Assertion
and Defense of Indemnification Claims.

         (a) Assertion of Claim. NEOGEN or SELLERS under Paragraphs 10.2 and
10.3, respectively ("Indemnified Party"), shall give notice to the other
("Indemnifying Party") as soon as

                                                                            -22-
<PAGE>

reasonably possible after the Indemnified Party has actual knowledge of any
claim to which the Indemnifying Party has an obligation to indemnify, including
the amount, if known, and shall promptly supply any other information in
possession of the Indemnified Party supporting the claim. The omission by the
Indemnified Party to give Notice as soon as reasonably possible will not relieve
the Indemnifying Party of its indemnification obligations, unless the failure to
give notice to the Indemnifying Party materially prejudices the Indemnifying
Party or notice is given after the end of the survival period of the applicable
representation of warranty or other basis of the claim. All indemnification
claims must be asserted by giving notice within the survival period of the
applicable representation or warranty or other basis for the claim. NEOGEN shall
have the right to set off any Damages it may incur against the amount it owes
SELLERS. This right of set off shall be in addition to any other rights or
remedies NEOGEN may have against SELLERS.

         (b) Defense of Undisputed Claim. The Indemnified Party will permit the
Indemnifying Party (at its expense) to assume the defense of any third party
claim in any litigation. The Indemnifying Party may settle or compromise any
third party claim or litigation only with the consent of the Indemnified Party,
which consent shall not be unreasonably withheld. The Indemnified Party shall
have the right at all times to participate in the defense, settlement,
negotiations or litigation relating to any third party claim or demand at its
own expense. If the Indemnifying Party does not assume the defense of any matter
which it has an obligation to indemnify, then the Indemnified Party shall have
the right to defend any such third party claim or demand, and will be entitled
to settle any such claim or demand in its discretion, all at the expense of the
Indemnifying Party. In any event, the Indemnified Party will cooperate in the
defense of any such action at the expense of the Indemnifying Party and the
pertinent records of each party shall be available to the other with respect to
the defense.

         (c) Defense of Disputed Claim. Should an Indemnifying Party provide
Notice to the Indemnified Party regarding a claim or action by a third party for
which the Indemnifying Party denies liability, the Indemnified Party shall give
the Indemnifying Party a reasonable opportunity: (1) to conduct any proceedings
or negotiations in connection therewith; (2) to take all other required steps or
proceedings to settle or defend any third party action; or (3) to employ counsel
to contest any third party claim or action in the name of the Indemnified Party
or otherwise. If the Indemnifying Party desires to assume the defense of the
third party claim or action, it shall promptly give Notice to the Indemnified
Party. The Indemnifying Party and the Indemnified Party may participate in the
defense at their own expense.

         10.6 Limitation on Recovery. SELLERS' obligation to indemnify NEOGEN
under this Section 10 shall not exceed a total expenditure, for any and all
claims, demands, actions, proceedings, liabilities, losses, damages, costs and
expenses, of Three Million Two Hundred Thousand Dollars ($3,200,000).

         10.7 Limitation of Liability. IN NO EVENT SHALL ANY PARTY BE LIABLE TO
THE OTHERS FOR ANY SPECIAL, CONSEQUENTIAL, INCIDENTAL OR INDIRECT DAMAGES,
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, ARISING OUT OF THIS AGREEMENT,
WHETHER OR NOT SUCH PARTY IS ADVISED OF THE POSSIBILITY OF SUCH DAMAGES, EXCEPT
FOR INSTANCES INVOLVING FRAUD AND INTENTIONAL NON-DISCLOSURE, AND EXCEPT WHERE
SUCH IS ALLEGED BY A THIRD PARTY

                                                                            -23-
<PAGE>

CLAIMANT FOR WHICH ONE OF THE PARTIES HERETO IS ENTITLED TO INDEMNIFICATION
HEREUNDER.

ARTICLE 11 MISCELLANEOUS

         11.1 Successors; Assignability. Each party may assign its rights
hereunder without the consent of the other parties; provided the assignor shall
remain fully liable for all obligations pursuant to this Agreement. This
Agreement shall inure to the benefit of and be binding upon the executors,
administrators, successors and permitted assigns of the parties hereto.

         11.2 Costs and Expenses. Whether or not the transactions contemplated
by this Agreement are consummated, SELLERS will pay their own expenses, and
NEOGEN will pay its own expenses, in connection with the negotiation, execution,
delivery and performance of this Agreement, including without limitation the
expenses of their respective counsel, accountants and other experts.

         11.3 Other Agreements Superseded; Waiver and Modification, Etc. This
Agreement, any agreement listed on Schedule 3, the Assignment Of Immunity From
Suit Under Gen-Probe's Kohne Patents, the Assignment of Orion and Institut
Pasteur Licenses and the Assignment of Gene-Trak Licenses, supersede all prior
agreements or understandings, written or oral, between the parties relating to
the subject matter hereof, and incorporates the entire understanding of the
parties with respect to such subject matter. This Agreement may be amended,
supplemented or waived only by a written instrument signed by an authorized
representative of all parties. The parties expressly acknowledge and agree that,
except for the licenses expressly granted NEOGEN in Section 7.1 and the
assignment of Intellectual Property Rights listed on Schedules 3 and 4, no other
rights of any kind to the Intellectual Property Rights owned by SELLERS or its
third-party licensors (including, without limitation, implied licenses) are
granted to NEOGEN under this Agreement. NEOGEN hereby expressly disclaims any
implied licenses under any other patents held by SELLERS and/or their licensor,
The Regents of the University of California.

         11.4 Notices. Any notice under or relating to this Agreement shall be
given in writing and shall be deemed sufficiently given and served for all
purposes (a) when personally delivered or transmitted by facsimile, or (b) two
(2) business days after a writing is deposited in the United States mail, first
class postage or other charges prepaid and registered, addressed as follows:

                                                                            -24-
<PAGE>

                  (a)      If to SELLERS:

                           Vysis, Inc.

                           3100 Woodcreek Drive
                           Downers Grove, Illinois 60515
                           Attention: President & CEO
                           Facsimile: (630) 271-7078

                  (b)      If to NEOGEN:

                           Neogen Corporation
                           620 Lesher Place
                           Lansing, Michigan  48912-1595
                           Attention: President & CEO
                           Facsimile: (517) 372-0108And a copy to:

                           Richard C. Lowe
                           Foster Zack & Lowe, P.C.
                           2125 University Park Drive, Suite 250
                           Okemos, MI 48876
                           Telephone and facsimile: (517) 706-5801
                           Email: dick.lowe@fosterzacklowe.com

         11.5 Parties in Interest. Nothing in this Agreement, express or
implied, is intended to confer any rights or remedies under or by reason of this
Agreement on any person other than the parties to it and their respective
permitted successors and assigns, nor is anything in this Agreement intended to
relieve or discharge any obligation of any third person to any party hereto or
give any third person any right of subrogation or action over against any party
hereto.

         11.6 Governing Law; Jurisdiction; Venue. This Agreement shall be
construed in accordance with and governed by the laws of the State of Michigan,
without giving effect to the principles of conflict of laws thereof. The parties
agree that any action permitted by this Agreement shall be brought in the court
of appropriate jurisdiction in Kent County, Michigan or U.S. District Court for
the Western District located in Grand Rapids, Michigan. The parties consent to
jurisdiction and waive all claims of improper venue and forum non conveniens.

         11.7 Fair Construction/Difference in Facts. This Agreement has been
negotiated and prepared jointly by both parties and shall not be construed for
or against any party but shall be given a fair and reasonable construction in
accordance with the intention of the parties.

         11.8 Captions, References, Date. The Article and Section headings in
this Agreement are provided for convenient reference only and are not to be
considered in the interpretation of this Agreement. All references herein to
Article, Section, Schedule, etc. refer to the designated Article, Section,
Schedule, etc. of this Agreement.

                                                                            -25-
<PAGE>

         11.9 Severability. In the event that any of the provisions contained in
this Agreement shall, for any reason, be declared or held to be unreasonable,
unlawful, unenforceable or otherwise invalid in any respect, such term or
provision shall be deemed modified to the extent necessary to make it
enforceable, and in no event shall such declaration or holding affect the
validity of any other provision of this Agreement, all of which provisions shall
continue in effect in accordance with their terms.

         11.10 Counterparts. This Agreement may be executed in any number of
counterparts or using separate signature pages. Each such executed counterpart
and each counterpart to which such signature pages are attached will be deemed
to be an original instrument, and all such counterparts together will constitute
one and the same instrument.

         11.11 Relationship of the Parties. Both parties are independent
contractors under this Agreement. Nothing contained in this Agreement is
intended nor is to be construed so as to constitute SELLERS and NEOGEN as
partners or joint venturers with respect to the subject matter of this
Agreement. Neither party hereto shall have any express or implied right or
authority to assume or create any obligations on behalf of or in the name of the
other party or to bind the other party to any other contract, agreement or
undertaking with any third party.

         11.12 Brokerage. Each party represents and warrants to the other that
it has dealt with no broker or finder in connection with any of the transactions
contemplated by this Agreement and, insofar as each party knows, no broker,
finder or other Person is entitled to any brokerage commission or finder's fee
in connection with any of such transactions. SELLERS agree to indemnify and hold
harmless NEOGEN and NEOGEN agrees to indemnify SELLERS from and against any loss
or damage incurred by reason of any other brokerage commission or finder's fee
alleged to be payable because of any act, omission or statement of the
indemnifying party.

         11.13 Publicity.

         (a) Upon the Closing, NEOGEN shall issue the press announcement
attached as Exhibit E hereto.

         (b) SELLERS and NEOGEN may each be required to attach this Agreement as
an exhibit to documents required to be filed with the Securities Exchange
Commission pursuant to the Securities Act of 1933 and the Securities Exchange
Act of 1934, each as amended. SELLERS and NEOGEN shall cooperate in determining
whether confidential treatment should be sought for all or any part of such
filings, and, if it is agreed that confidential treatment should be sought, each
party shall use reasonable best efforts to secure such confidential treatment.

         (c) The Parties will cooperate on any other announcement where the name
of the other Party is used in a way not expressly authorized under this
Agreement.

         11.14 Arbitration. (a) Demand for Arbitration. Except regarding a claim
for fraud or injunctive relief or pursuant to Paragraphs 9.4 and 9.5, any
controversy, dispute or claim arising out of, in connection with, or in relation
to, the construction, performance or breach of this Agreement, including without
limitation, the validity, scope and enforceability of this Paragraph 11.14,
shall be adjudicated by arbitration conducted in Grand Rapids, Michigan, in
accordance with the then existing rules for commercial arbitration of the
American Arbitration Association ("AAA")

                                                                            -26-
<PAGE>

or any successor organization by a panel of three (3) arbitrators. The
provisions of this Paragraph 11.14 shall control over any conflicting rules and
procedures of AAA. The demand for arbitration shall be delivered in accordance
with the Notice provisions of this Agreement. The burden of proof in the
arbitration shall not be affected by which party initiates the arbitration. Each
party shall be entitled to reasonable prehearing discovery, including without
limitation exchange of witness lists, depositions under oath of witnesses at a
mutually convenient location and document requests.

         (b) Selection of Arbitrators. Within ten days after receipt of such
demand, the parties shall jointly request a list of arbitrators, all of whom
must be licensed to practice law in Michigan, from the AAA from the Grand
Rapids, Michigan area. None of the prospective arbitrators shall have had at any
time any conflict or opposing interest against either SELLERS or NEOGEN. Upon
receipt of the list of arbitrators, each party shall mark selections and
rejections and resubmit the list to the AAA. The selections and rejections shall
take place within ten days after receipt of the proposed arbitrators from the
AAA. The parties shall cooperate with the AAA and the appointed arbitrator for
the purpose of setting an expeditious hearing, which shall be conducted in Grand
Rapids, Michigan.

         (c) Costs and Expenses. The costs of the arbitration, the fees and
expenses of the arbitrator, hearing room, and court reporter ("Arbitrator
Costs") shall be borne by the nonprevailing party. Each party may be represented
by counsel if it so chooses.

         (d) Attorneys Fees. The prevailing party in the arbitration shall be
entitled to attorneys fees and expenses incurred in connection with the
arbitration ("Legal Costs") and interest on the award at the prime rate of
interest published in the Wall Street Journal plus 2% from the date the
arbitration was initiated until the date of payment. The arbitrators shall, as
part of the determination of the award, determine which party is the
nonprevailing party for purposes of determining who must pay the Arbitrator
Costs and the Legal Costs of the prevailing party.

         (e) Binding Nature of Decision. The parties intend this agreement to
arbitrate to be valid, enforceable and irrevocable. The decision of the
arbitrator with respect to all matters, which shall be rendered no later than 45
days after the date the hearing begins, shall be final and binding upon the
parties and judgment on such award may be entered by either party in any court
having jurisdiction over the person or property of the party against whom such
award is sought to be enforced. The parties stipulate that these arbitration
provisions shall be a complete defense to any suit, action or proceeding
instituted in any federal, state or local court, or before any administrative
tribunal with respect to any dispute, controversy or alleged breach of this
Agreement. The arbitration provisions of this Agreement shall survive any
termination or expiration of this Agreement.

                                                                            -27-
<PAGE>

         11.15 Sole Remedy. Except for injunctive relief for violations of
Section 9.4 or 9.5, the indemnification provided in Section 10 hereof (subject
to the limitations contained therein) shall be the sole and exclusive remedy for
any and all matters arising out of, or related to, this Agreement.

         11.16 Attorneys' Fees. The prevailing party in any litigation, except
for litigation involving requests for injunctive relief, shall be entitled to
attorneys fees and expenses incurred in connection with the such litigation and
interest on the award at the prime rate of interest published in the Wall Street
Journal plus 2% from the date the litigation was initiated until the date of
payment.

         11.17 Injunctive Relief. Sellers acknowledge that a breach of any of
the covenants, agreements or promises contained in Paragraphs 9.4 or 9.5 will
result in irreparable injury to NEOGEN for which there will be no adequate
remedy at law, and that, in the event of such a breach or threatened breach,
NEOGEN shall be entitled to obtain a temporary restraining order, preliminary
injunction and permanent injunction restraining Sellers from engaging in any of
the activities prohibited by Paragraphs 9.4 and 9.5. SELLERS agree that the term
of the covenant contained in Paragraph 9.5 shall be increased by the number of
days during which any of SELLERS is found to be in violation of the covenant.


                  (remainder of page left blank intentionally)

                                                                            -28-
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Asset
Purchase Agreement to be effective as of the date first written above:


VYSIS, INC.

By:

--------------------------------
Name: William E. Murray
Title:  Vice President


GENE-TRAK, INC.

By:

--------------------------------
Name:  William E. Murray
Title:  Vice President


GENE-TRAK SYSTEMS INDUSTRIAL
DIAGNOSTICS CORPORATION

By:

--------------------------------
Name:  William E. Murray
Title:  Vice President


NEOGEN CORPORATION

By:

--------------------------------
Name:  James L. Herbert
Title:  President & CEO

                                                                            -29-