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                                                                   EXHIBIT 10.83



                WORLDWIDE MEDICAL PRODUCT DISTRIBUTION AGREEMENT



         This Worldwide Medical Product Distribution Agreement (the "Agreement")
is effective as of May 31, 1996, between Collagen Corporation, a Delaware
corporation with an address at 2500 Faber Place, Palo Alto, California 94303
("Distributor") and Tissue Technologies, Inc., a corporation organized under the
laws of California, with its principal place of business at 1370 Green Street,
San Francisco, California 94109 (the "Supplier").

                  WHEREAS, Supplier is engaged in the development of products
comprised of E-PTFE tubes for soft tissue augmentation and management of facial
wrinkles;

                  WHEREAS, Distributor is engaged in the marketing and sale of
medical products for soft tissue augmentation and management of facial wrinkles;

                  WHEREAS, Distributor wishes to be appointed Supplier's
exclusive distributor of the Products in the Territory (as such terms are
hereinafter defined), and Supplier wishes to appoint Distributor as its sole
exclusive distributor;

                  WHEREAS, Distributor wishes to purchase Product(s) from
Supplier, and Supplier wishes to sell Product(s) to Distributor for exclusive
marketing and sale of the Product(s) in the Territory on the terms and subject
to the conditions set forth herein.

         NOW THEREFORE, in consideration of the premises and of the mutual
covenants of the parties hereto, the parties agree:



1.       DEFINITIONS

         1.1 "First Commercial Sale" shall mean the first transfer of title to a
Product by Distributor to a third party, excluding Distributor's subsidiaries or
affiliates, for monetary consideration.

         1.2 "Government Agency" shall include all local, national, and
supranational bodies with the legal authority to establish rules, regulations,
standards and guidelines (or to issue certificates of compliance with these),
covering the design, manufacturing, and marketing of the Products in the
Territory. This will include without limitation the United States Food and Drug
Administration.

         1.3 "Initial Period" shall mean the term beginning as of the First
Commercial Sale of Product(s) and ending on *** .


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         1.4 "Intellectual Property Rights" shall include all patents,
copyrights, and other proprietary rights or applications therefor, including
Supplier's rights under the Exclusive License Agreement between Supplier and The
Regents of the University of California ("The Regents") dated December 1, 1993
appended hereto as Exhibit A, which the Supplier may at any time during the term
of this Agreement own, license, adopt, use, or register with respect to the
Products.

         1.5 "Net Sales" means the amounts actually received from the sale of
Products by Distributor or its subdistributor for cash or other forms of
monetary consideration, in accordance with Generally Accepted Accounting
Principles, less the following deductions: (a) allowances, rejections, returns,
and volume discounts, (b) freight , transport packaging, insurance charges
associated with transportation, and (c) taxes, tariff, or import/export duties.

         1.6 "Product(s)" means any and all of those products described in
Schedule A, and identified by a separate Product Specification (as hereinafter
defined).

         1.7 "Product Specification" shall mean any document that defines the
manufacturing requirement of a Product, including but not limited to packaging
configuration, labeling, material components, and information relating to
material composition and release tests that may be certified pursuant to a
Certificate of Analysis. Each Product Specification shall be incorporated into
this Agreement as an Appendix to Schedule A.

         1.8 "Territory" means any and all of the countries, or parts thereof,
referred to in Schedule B.


2.       APPOINTMENT OF THE DISTRIBUTOR

         2.1 Supplier hereby appoints the Distributor, and the Distributor
hereby accepts this appointment, as Supplier's sole and exclusive (subject to
Section 5.9, Minimum Purchase) authorized distributor, with the right to grant
subdistributorships, for the promotion, marketing, distribution and sale of
Products in the Territory. As a result, Supplier will not sell Products in the
Territory, other than through Distributor.

3.       MILESTONE PAYMENTS

         3.1 So long as the Supplier is not in breach of any material provision
of this Agreement, and upon the occurrence of the following events, the
Distributor shall make the following milestones payments to the Supplier:

                  (a) *** upon the execution of this Agreement;

                  (b) *** within *** days of Supplier's notice to the
Distributor of the issuance of a United States patent claiming Supplier's soft
tissue augmentation device; and

                  (c) *** upon   *** of the Effective Date.

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4.       PRICE, FORECASTS, PURCHASE ORDER, DELIVERY, ACCEPTANCE, TRANSFER OF
         TITLE, FEES AND PAYMENT

         4.1 Prices. Subject to the provisions of this Agreement, the Supplier
shall sell Products to the Distributor at the unit prices set forth in Schedule
A. The Purchase Price constitutes payment for the manufacturing cost of the
Products and royalties due Supplier for Distributor's exclusive distribution
right. Nothing herein shall obligate the Distributor to pay any additional past
or future royalties to any third party, unless expressly included in this
Agreement. The unit price set forth in Schedule A includes the cost of the
Product, all expenses relating to packaging and labeling of the Products, all
freight insurance premiums, and all freight charges to the mutually agreed upon
delivery site(s) listed in Schedule D.

         4.2 Forecasts. The Distributor shall provide non-binding, rolling
twelve (12) month forecasts of Distributor's anticipated requirements of
Products, updated *** , throughout the term of this Agreement. Such twelve (12)
month forecast shall be based on Distributor's fiscal year cycle, beginning on
July 1st and ending on June 30th.

         4.3      Purchase Orders.

                  (a) Purchase orders shall be submitted by the Distributor in
writing. During the Initial Period, purchase orders in any given year must meet
the minimum purchase requirements set forth in Schedule C. In the event that the
Supplier is unable to fulfill the terms of any purchase order, the Supplier
shall so inform the Distributor in writing within five (5) business days of the
Supplier's receipt of such purchase order. Any orders in the ordinary course of
business, consistent with normal ordering practices, that are rejected or
unfullfilled by Supplier shall be deducted from the minimum purchase
requirement, in any given year, as set forth in Schedule C. Purchase orders
shall be deemed accepted and binding by the Supplier unless the Supplier rejects
any purchase order in writing by return facsimile within five (5) business days
of the Supplier's receipt of such purchase order.

                  (b) Distributor, may at its option, either reschedule delivery
of any Products or cancel any order or portion thereof, upon written notice to
Supplier. A "reschedule" is defined as changing all or any portion of those
Products scheduled for shipment on any ship date by moving the ship date later
in time. Distributor shall have a right to cancel or reschedule any order for
later shipment provided such request is received by Supplier at least thirty
(30) days in advance of the original ship date.

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         4.4 Delivery. Products shall be sold to the Distributor F.O.B. delivery
site(s) listed in Schedule D. Supplier shall deliver an invoice to Distributor
for each unit of Product sold to Distributor pursuant to Distributor's purchase
order. Distributor agrees to conform its purchase orders to the minimum quantity
of Products shipped to a particular delivery site as set forth in Schedule D.

         4.5 Acceptance. The Distributor shall within ten (10) business days
inspect each shipment of Products after delivery. In the event the Distributor
determines that any shipment, or part thereof, is incomplete, damaged or
defective, the Distributor shall so inform the Supplier in writing within such
ten (10) business days. All Products shall be deemed accepted by the Distributor
unless any such delivery, or part thereof, is rejected in writing by return
facsimile within such ten (10) business days period.

         4.6 Transfer of Title. Title to and ownership of Products shall pass to
the Distributor upon acceptance by the Distributor, and the Distributor shall
thereafter be responsible for any damage or loss of such Products. Supplier
shall bear all risk of loss of, or damage to, all units of Products up to the
time the Products are accepted by Distributor.

         4.7 Fees. The Distributor shall be responsible for payment of customs
and other duties and any taxes in the Territory and for obtaining any import and
export licenses that may be required by proper authorities in the Territory.

         4.8 Payments. Payment for Products shall be made in United States
dollars. During the Initial Period, Distributor shall pay Supplier within ***
after receipt of an invoice, and acceptance of the Products by the Distributor.
Subsequent to the Initial Period, Distributor shall pay Supplier in arrears,
within *** after Distributor's quarter end close. The calculation for such
payments are described in Schedule A.


5.       GENERAL OBLIGATIONS OF THE DISTRIBUTOR

         5.1 Inventory Levels. The Distributor shall maintain an inventory of
Products reasonably sufficient to meet *** of anticipated sales of the Products
in the Territory. The Distributor shall store the Products under secure
conditions and in compliance with all pharmaceutical or medical device laws
applicable to storage of the Products.

         5.2 Independent Agent. The Distributor shall conduct its business in
the purchase and resale of Products as a principal for its own account and at
its own expense and risk. The Distributor, its agents and employees are not the
legal representatives, employees or agents of Supplier for any purpose and have
no right or authority to incur any expenses on behalf of Supplier or to assume
or create, in writing or otherwise, any obligations of any kind, express or
implied, in the name of or on behalf of Supplier. Nothing contained in this
Agreement shall create the relationship of partners, joint ventures, employer
and employee, principal and agent, or any similar relationship, between Supplier
and the Distributor.

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         5.3      Regulatory Approvals and Compliance.

                   (a) Excluding the United States, Distributor shall obtain and
own all regulatory approvals, certificates, registrations, licenses, and permits
related to the Products unless prohibited by local law. In the event that
necessary approvals, certificates, registrations, licenses, and permits required
to sell and distribute the Products in the Territory are required by local law
to be owned by, or held in the name of Supplier, Supplier agrees that it shall
provide reasonable assistance to Distributor in order to obtain any and all
applicable regulatory approvals required by Government Agencies under the laws
and/or regulations of any jurisdiction in order to market the Products within
the Territory, including but not limited to, meeting relevant standards and
guidelines, preclinical, clinical, and safety approvals required by Government
Agencies. Regulatory approvals, certificates, registrations, licenses, and
permits filed during the term of this Agreement, excluding U.S. filings, and in
the name of Supplier shall be assigned to Distributor upon termination of this
Agreement. Distributor shall promptly inform Supplier of any changes in
regulatory or compliance status that might significantly affect the marketing of
the Products in the Territory;

                   (b) the Distributor agrees not to sell or distribute the
Products in any country within the Territory until such time as all product
licenses and approvals required by the laws of such country have been obtained;

                   (c) the Distributor shall comply with any recalls for the
Products issued by Supplier or applicable Government Agencies;

                   (d) the Distributor shall maintain a record of any customer
complaints or comments and promptly forward information relating to such
complaints or comments to Supplier; the Distributor shall also disclose to
Supplier promptly via facsimile any Medical Device Report ("MDR") related to the
Products subject to the Code of Federal Regulations, 21 CFR Part 803, and/or
subject to the Medical Device Vigilance System of the European Commission
Guidelines, MED DEV 03/93, rev 2.

         5.4 Sales Effort. The Distributor shall employ an appropriate number of
sales personnel, maintain a suitable organization, and use its commercially
reasonable efforts to actively market and sell the Products in the Territory.

         5.5 Marketing Effort. The Distributor shall use its commercially
reasonable efforts to promote the Products to persons engaged in all appropriate
medical specialties, including but not limited to plastic surgery, dermatology,
ENT (ear, nose, and throat), aesthetic and cosmetic medicine and other related
areas of the medical profession.

         5.6 Liability Insurance. The Distributor shall, if required by local
law, obtain, and pay premiums and all costs associated with liability insurance
in an amount sufficient to satisfy local laws and commercial practices.

         5.7 License Fees and Taxes. The Distributor shall pay all license fees,
taxes and other fees including, but not limited to, sales, use, service use,
occupation, service occupation, personal property and excise taxes, assessments
or taxes which may be assessed or levied by any national, state or local
government, and any departments and subdivisions thereof, against the
Distributor for the distribution and sale of the Products which are ordered by
the Distributor and are under the Distributor's control.

         5.8 Import/Export Licenses. The Distributor shall, at its own expense,
pay all import and export licenses and permits, pay customs charges and duty
fees, and take all other actions required to accomplish the export and import of
the Products purchased by the 


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Distributor; the Distributor understands that Supplier is subject to regulation
by agencies of the U.S. Government (including without limitation the U.S.
Department of Commerce) which prohibit export or diversion of certain technical
products to certain countries; the Distributor warrants that it will comply in
all respects with the export and re-export restrictions set forth in the export
license for every Product purchased under this Agreement.

         5.9      Minimum Purchase Requirement.

                  (a) During the Initial Period and subject to Section 4.3(a),
the Distributor agrees to purchase the number of units of Product(s) represented
by the United States dollar amount set forth for each time period in Schedule C.
In the event that (i) the Distributor fails to satisfy such minimum purchase
requirement during the Initial Period, (ii) the Supplier provides written notice
of such failure to the Distributor, and (iii) the Distributor fails to cure such
condition within ninety (90) day of its receipt of such notice, the Supplier
shall have the option to either (i) revert Distributor's exclusive distribution
right to a non-exclusive distribution right, or (ii) terminate this Agreement.

         (b) For each twelve-month period after the Initial Period and until the
termination of this Agreement, to maintain Supplier's exclusive appointment of
Distributor, the Distributor agrees to purchase the number of units of
Product(s) represented by the United States dollar amount set forth for each
time period in Schedule C. In the event that (i) the Distributor fails to
satisfy such minimum purchase requirement for any twelve-month period subsequent
to the Initial Period, (ii) the Supplier provides written notice of such failure
to the Distributor, and (iii) the Distributor fails to cure such condition
within ninety (90) day of its receipt of such notice, the Distributor shall be
deemed to be a nonexclusive distributor of the Products and the Supplier shall
be entitled to appoint another nonexclusive distributor for the Territory. If
Distributor's rights become non-exclusive, then all minimum purchase
requirements shall become null and void.

         (c) Within the United States or the European Economic Area, if in any
given period (i) the Supplier is unable to meet all applicable regulatory
requirements by Government Agencies of a particular country relating to
Supplier's obligations under this Agreement, and therefore Distributor is unable
to obtain regulatory approval in such particular country, or (ii) the Supplier
and Distributor fail to agree upon Product Specifications within *** after
receiving all applicable regulatory approvals required by Government Agencies in
a particular country, and Distributor's supply of Product(s) is interrupted,
then Distributor's minimum purchase requirement for such interrupted period
shall be reduced by *** for so long as Supplier is unable to meet Distributor's
supply requirement.

         5.10 Financial Audit. Payments made by Distributor to Supplier,
excluding payments made pursuant to an invoice for delivery of Product(s) during
the Initial Period, shall be subject to reasonable audit by Supplier upon sixty
(60) days prior written notice, and at Supplier's expense, not more often than
once in any twelve month period. Supplier's audit shall be limited to sales
reports, order entry, and shipping records on Product(s). If such audit
discloses an error between reported numbers and actual numbers by 5% or more,
then Distributor shall pay Supplier's audit expenses.

6.       GENERAL OBLIGATIONS OF SUPPLIER

         6.1 Fulfillment of Purchase Orders. Following receipt and acceptance of
a purchase order from the Distributor for Products, Supplier shall use all
commercially reasonable endeavors to fulfill such purchase order without undue
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manufacturing lead times) and to deliver the Products in accordance with the
Distributor's instructions.

         6.2 Initial Product Delivery. Supplier shall use its commercially
reasonable efforts to manufacture and deliver at least *** units of Products by
*** .

         6.3 Manufacturing Compliance. Supplier shall manufacture and deliver
Products which meet the Product Specifications, including packaging and labeling
in multiple languages as needed, mutually agreed upon by the parties and which
conform at all times to applicable regulations. Supplier shall have the primary
responsibility for manufacturing compliance of the Products in the Territory as
required by Government Agency rules and regulations, including but not limited
to, recalls of Products. Supplier shall provide at least ninety (90) days
written notice to the Distributor regarding any proposed changes, modifications,
deletions or additions to be made to the Product(s) and shall consult with the
Distributor prior (i) to discontinuing the manufacture, supply or sale of any
type of Product, (ii) to making changes in materials or design, or (iii) to
adding improvements to any Product. Supplier agrees that prior to implementing
any manufacturing changes, it will have received notice from Distributor that
such changes have been approved by all relevant Government Agencies.

         6.4 Certification, Audits, and Second Supply. The Supplier shall use
its commercially reasonable efforts to qualify its manufacturing contractor(s)
as ISO certified facilities by *** , and shall obtain the permission of its
manufacturing contractor(s) to allow the Distributor to audit the facilities of
such manufacturing contractor(s). The Supplier shall use its commercially
reasonable efforts to establish (or contract for) a second Product manufacturing
capability promptly upon the first sale of a commercial lot of Product.

         6.5 Regulatory Assistance. Supplier agrees that it shall provide
reasonable assistance to Distributor in order to obtain any and all applicable
regulatory approvals required by Government Agencies under the laws and/or
regulations of any jurisdiction in order to market the Products within the
Territory, including but not limited to, meeting relevant standards and
guidelines, preclinical, clinical, and safety approvals required by Government
Agencies. Supplier shall promptly inform Distributor of any changes in
regulatory or compliance status that might significantly affect the marketing of
the Products in the Territory.

         6.6 Regulatory Compliance. Upon receipt of a notification by
Distributor, relating to an MDR, the Supplier shall notify the Food and Drug
Administration within five (5) business days in compliance with 21 CFR Part 803,
and/or in accordance with the Medical Device Vigilance System of the European
Commission Guidelines, MED DEV 03/93, rev 2.

         6.7 Marketing Assistance. Supplier shall, at its own expense, from time
to time and at the request of the Distributor, provide the Distributor with
information, including but not limited to clinical protocol and data results,
and assistance reasonably related to the marketing of Products in the Territory.
Supplier shall, at its own expense, make the mutually agreed upon quantities,
not to exceed *** units per year, of its promotional materials and demonstration
products (not for human use), including in multiple languages as needed,
available to the Distributor, for Distributor's use in promoting the Products in
the Territory. Supplier's mutual agreement to make the quantities of
demonstration product shall not be unreasonably withheld.

         6.8 Prelaunch Assistance. The Supplier will, at its own expense,
provide such Distributor training, marketing, and clinical support as reasonably
requested by the Distributor in order for Distributor to effectively launch the
marketing and sales of Products in any country of the Territory. If such
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the Northern California Bay Area, then Distributor shall only pay Supplier's
travel and out-of pocket expenses provided that Supplier provides reasonable
documentation for such expenses. Such time commitment shall not exceed 35 hours,
exclusive of travel time, over the twelve month period after the Effective Date.

         6.9 Postlaunch Assistance. The parties anticipate that the Distributor
and Drs. Robert Schindler and Corey Maas, founders of the Supplier, will enter
into consulting arrangements separately for Supplier's attendance at major
national and regional trade shows and educational forums where similar or
competitive products are displayed and to present the Products fairly at such
shows and workshops.


7.       INTELLECTUAL PROPERTY

         7.1 Grant of License.

         (a) The Supplier hereby grants to the Distributor the sole and
exclusive, worldwide, fully-paid up license, with the right to sublicense, under
the Supplier's Intellectual Property Rights and subject to the rights granted by
The Regents, to use such Intellectual Property Rights solely in connection with
the sale and other distribution of Products in the Territory.

         (b) Distributor shall have a first right of refusal to distribute any
biocompatible product owned by Supplier for use in soft tissue augmentation and
management of facial wrinkles. The Distributor and Supplier agree to negotiate
in good faith the terms of such distribution right, including but not limited to
any manufacturing obligations, and shall cooperate in the finalization of a
definitive agreement within *** after Distributor's notice of acceptance of such
distribution right.

         7.2 Assistance. The Distributor shall promptly notify the Supplier (i)
of any claims or objections that the Distributor's use of the Intellectual
Property Rights in connection with the marketing or sale of the Products may or
will infringe any third party patent, copyright, trademarks, trade names, or
other proprietary rights, and (ii) of any and all third party infringements,
imitations, illegal use, or misuse of the Intellectual Property Rights which
come to its attention.

         7.3 Patent Issuance Fee. In the event and solely upon the occurrence of
the issuance of a United States patent claiming Supplier's soft tissue
augmentation device described in Schedule A, the Distributor shall pay Supplier
the total sum of *** which represents payment for the license fees set forth in
Section 4.1 of the Exclusive License Agreement, dated December 1, 1993, between
The Regents and the Supplier. Supplier acknowledges that it is solely
responsible for paying The Regents any and all license fees pursuant to Section
4.1 of the Exclusive License Agreement.

         7.4 University of California. Subsequent to the first quarter in which
the Distributor makes sales of the Product, and each quarter thereafter in which
the Distributor makes sales of the Products, the Supplier will make the royalty
payments due to The Regents pursuant to Section 5 of the Exclusive License
Agreement, dated December 1, 1993, between The Regents and the Supplier.
Distributor shall pay Supplier the royalty payments due to The Regents pursuant
to Section 5 of the Exclusive License Agreement, dated December 1, 1993, between
The Regents and the Supplier. If the Distributor's rights become non-exclusive,
then royalty payments will be limited to those in Section 5.1 of the Exclusive
License Agreement and will not include the minimums in Section 5.5.

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         7.5 Trademarks. Nothing in this Agreement will be construed as
conferring any right to use in advertising, pubilicity, or other promotional
activites any name, trade name, trademark, or other designation of either party
hereto by the other (including contraction, abbreviation or simulation of any of
the foregoing). Distributor shall solely own and maintain, at its expense, any
and all trademarks used in its distribution of the Products in the Territory.
Supplier shall not register any such trademark(s) of Distributor in any country
of the Territory for its own or third party use.


8.       CONFIDENTIAL INFORMATION

         8.1 "Confidential Information" shall mean any confidential, secret, or
proprietary information relating to the scientific and/or business affairs of
either party, regardless of whether such information is specifically designated
as confidential, and regardless of whether such information is in written, oral,
electronic, or other form. Such Confidential Information may include, but is not
limited to, trade secrets, know-how, inventions, technical data or development
activities, product and marketing plans, customer and supplier information, and
legal and regulatory activities. Each party shall treat as confidential all
Confidential Information provided by the other party, shall not use such
Confidential Information except as expressly set forth herein or otherwise
authorized in writing, shall implement reasonable procedures to prohibit the
disclosure, unauthorized duplication, misuse or removal of the Confidential
Information and shall not disclose such Confidential Information to any third
party. Without limiting the foregoing, each of the parties shall use at least
the same procedures and degree of care to prevent the disclosure of Confidential
Information as it uses to prevent the disclosure of its own confidential
information of like importance, and shall in any event use no less than
reasonable procedures and a reasonable degree of care.

         8.2 Exceptions. Notwithstanding the above, neither party shall have
liability to the other with regard to any Confidential Information that:

                  (a) was generally known and available in the public domain at
the time it was disclosed, or becomes generally known and available in the
public domain through no fault of the receiver;

                  (b) was known to the receiver at the time of disclosure as
shown by the files of the receiver in existence at the time of disclosure;

                  (c) is disclosed with the prior written approval of the
discloser;

                  (d) was independently developed by the receiver without any
use of the Confidential Information and by employees or other agents of the
receiver who have not been exposed to the Confidential Information, provided
that the receiver can demonstrate such independent development by documented
evidence prepared contemporaneously with such independent development;

                  (e) becomes known to the receiver from a source other than the
discloser without breach of this Agreement by the receiver and in a manner which
is otherwise not in violation of the discloser's rights;

                  (f) is disclosed pursuant to the order or requirement of a
court, administrative agency, or other governmental body; provided, that the
receiver shall provide reasonable advance written notice thereof to enable the
discloser to seek a protective order or otherwise prevent such disclosure, by
asserting the confidential nature of the information sought.


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         8.3 The provisions of this Section 8 shall be in full force and effect
for five (5) years after the termination of this Agreement.

9.       INDEMNIFICATION AND REPRESENTATION

         9.1 Indemnification by the Distributor.The Distributor shall indemnify,
defend, and hold the Supplier harmless from and against any and all third party
claims relating to and/or arising out of the marketing, distribution and sale of
the Products, where and to the extent the damages are alleged to have been
caused by the fault of the Distributor, its employees or agents.

         9.2 Indemnification by the Supplier. The Supplier shall indemnify,
defend, and hold the Distributor harmless from and against any and all third
party claims relating to and/or arising out of (i) the manufacture of Products,
including but not limited to any product, manufacturing, or labelling defect in
the Product, (ii) infringement of third party patent, copyright, trademarks,
trade names, or other proprietary rights, and (iii) any failure by Supplier to
act in accordance with applicable laws and regulations in the Territory in
connection with the Products.

         9.3 Representation by the Supplier. The Supplier hereby represents that
the Exclusive License Agreement between The Regents and the Supplier, dated
December 1, 1993 is in full force and effect, and that the Supplier has the
rights to grant Distributor the exclusive distribution rights under such
Exclusive License Agreement. The Supplier shall meet any and all obligations
under the Exclusive License Agreement to ensure that the License Agreement does
not terminate or become non-exclusive.


10.      LIMITED WARRANTY AND LIMITATION OF LIABILITY

         10.1 Supplier warrants that each Product sold to Distributor hereunder
will (i) be free from defects in materials and workmanship, (ii) be in
compliance with ISO 9001 standards by *** , (iii) be manufactured, packaged, and
labeled in accordance with the then prevailing Product Specifications, and (iv)
have a remaining shelf-life at the date of shipment of at least twenty-four (24)
months (the "Warranty Period"). If Distributor provides notice to Supplier
during the Warranty Period that a Product breaches this warranty, Distributor
shall, if requested by Supplier, return such Product to Supplier, or if not so
requested, dispose of such Product in accordance with Supplier's instructions.
The sole and exclusive remedy in the event of any breach of the foregoing
warranty is either (i) for the Distributor to so return or dispose of the
defective Products to Supplier (delivery or postage prepaid by Supplier) for
replacement in accordance with its standard warranty procedures, or (ii) for a
refund of the price paid by the Distributor for the defective Product if the
Supplier is unable to replace such defective Products within a reasonable time
period or at a commercially reasonable cost.

This warranty does not extend to any damage or failure which results from
alteration, accident, theft, misuse, abuse, abnormal use, or improper storage or
maintenance by Distributor.

THE DISTRIBUTOR ACKNOWLEDGES THAT SUPPLIER'S OBLIGATIONS AND LIABILITIES IN
RESPECT OF THE PRODUCTS AND THE DISTRIBUTOR'S APPOINTMENT ARE EXHAUSTIVELY
DEFINED IN THIS AGREEMENT. THE DISTRIBUTOR AGREES THAT THE EXPRESS OBLIGATIONS
AND WARRANTIES MADE BY SUPPLIER UNDER THIS AGREEMENT SHALL BE IN LIEU OF AND TO
THE EXCLUSION (TO THE FULLEST EXTENT PERMITTED BY LAW) OF ANY OTHER 

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WARRANTY, CONDITION, TERM OR UNDERTAKING OF ANY KIND, EXPRESS OR IMPLIED,
STATUTORY OR OTHERWISE RELATING TO ANYTHING SUPPLIED UNDER OR IN CONNECTION WITH
THIS AGREEMENT INCLUDING (WITHOUT LIMITATION) AS TO CONDITION, MERCHANTABILITY,
AND QUALITY.

         10.2 Supplier accepts liability without limit for death or personal
injury to the extent that it results from the negligence, breach of warranty, or
intentional conduct of Supplier and its employees and that it is caused by any
Product being defective and unsafe within the meaning of the applicable laws of
the Territory.

         10.3 EXCLUSION OF CONSEQUENTIAL DAMAGES. NOTWITHSTANDING ANYTHING TO
THE CONTRARY CONTAINED HEREIN, SUPPLIER SHALL NOT, UNDER ANY CIRCUMSTANCES, BE
LIABLE WHETHER IN CONTRACT, TORT (INCLUDING NEGLIGENCE) OR OTHERWISE TO THE
DISTRIBUTOR, ITS SALES REPRESENTATIVES, SUBDISTRIBUTORS OR DEALERS, OR ANY OTHER
THIRD PARTY INCLUDING ANY PURCHASER OF THE PRODUCTS HEREUNDER, FOR ANY
CONSEQUENTIAL, INCIDENTAL OR INDIRECT LOSS, DAMAGES, COST OR EXPENSE OF ANY KIND
WHATSOEVER AND HOWSOEVER CAUSED INCLUDING, WITHOUT LIMITATION, FOR ANY LOSS OF
PRODUCTION, LOSS OF PROFIT OR CONTRACTS AND LOSS OF GOODWILL ARISING OUT OF OR
RELATED TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREUNDER, EVEN IF
SUPPLIER HAS BEEN ADVISED OF THEIR POSSIBILITY.

11.      DURATION AND TERMINATION

         11.1 This Agreement shall become effective on the date first above
written and shall continue in effect, subject to termination under Sections 11.2
and 11.3 below, until the earlier of the tenth anniversary of the Effective
Date, or the last to expire of any patents claiming the Products.

         11.2 Supplier may terminate this Agreement at any time upon written
notice in the event that:

                   (a) the Distributor defaults in punctual payments in full of
the sums due under this Agreement or under any purchase orders, and such default
is not remedied within sixty (60) days after the Distributor has been served
with a written notice requiring such remedy; or

                   (b) the Distributor commits a breach of any material
provision of this Agreement, and such breach is not cured within sixty (60) days
after the Distributor has been served by Supplier with a written notice
requiring such cure; or

                   (c) the Distributor becomes insolvent, institutes proceedings
in bankruptcy or, under similar insolvency laws, for reorganization,
receivership, or dissolution.

         11.3 Distributor may terminate this Agreement at any time upon written
notice in the event that:

                   (a) the Supplier commits a breach of any material provision
of this Agreement, and such breach is not cured within sixty (60) days after the
Supplier has been served by Distributor with a written notice requiring such
cure; or

                  (b) the Supplier becomes insolvent, institutes proceedings in
bankruptcy or, under similar insolvency laws, for reorganization, receivership,
or dissolution; or


                                      -11-
<PAGE>   12
                   (c) the Supplier is unable to obtain a license to any third
party patent that prevents the sale or distribution of the Products in the
Territory.


12.      CONSEQUENCES OF TERMINATION

         In the event that this Agreement is terminated, the following
consequences shall follow:

         12.1 All the Distributor's rights under this Agreement shall cease and
no payment whatsoever shall be due to the Distributor for loss of goodwill,
anticipated profits or otherwise as a result of such proper termination. The
Distributor hereby waives any claim to receive any compensation as a consequence
of the proper termination of this Agreement. Supplier is relieved from any
obligation to make any further shipments hereunder, and may cancel all of the
Distributor's unshipped orders for Products, irrespective of previous written
acceptance by Supplier.

         12.2 Supplier shall repurchase at the Distributor's cost any remaining
inventory of the Distributor, except that if this Agreement is terminated during
the Initial Period, then Supplier shall only repurchase at the Distributor's
cost any remaining inventory above the minimum number of units of Products set
forth in Schedule C. Such repurchase shall occur within thirty (30) days after
the termination date. In the event Supplier fails to repurchase such Products,
Distributor shall have the right and option to (i) continue to sell its existing
inventory of such Products for a reasonable period following termination or
expiration, or (ii) deduct any repurchase cost of such Products from any
outstanding invoices due and payable pursuant to Section 12.3.

         12.3 All charges for Products unpaid at the date of termination shall
forthwith become due and payable within thirty (30) days after the termination
date.

         12.4 The Distributor shall return to Supplier all promotional/sales
materials within ninety (90) days. Both parties shall return to the other party
all Confidential Information in written, recorded, or other tangible form within
ninety (90) days.

         12.5 Pursuant to Section 5.3(a), Supplier shall assist with the
transfer of and/or assignment to Distributor any regulatory approvals,
certificates, registrations, licenses, and permits filed and maintained during
the term of this Agreement in the name of Supplier.

13.      MISCELLANEOUS PROVISIONS

         13.1 Governing Law. The construction, validity and performance of this
Agreement and any disputes arising hereunder be governed by the laws of the
State of California, exclusive of that body of law relating to choice of law,
and by the Uniform Commercial Code, as enacted in the State of California. Any
and all disputes, controversies or differences arising hereunder in connection
herewith shall be conducted in the English language.

         13.2 Notices. Any notice or report pursuant to this Agreement shall be
deemed duly given upon receipt if it is in writing and is sent by prepaid
registered air mail or express courier addressed to the party at the address set
forth at the beginning of this agreement, or to such other address as shall be
furnished in writing.

         13.3 Failure to Enforce. The failure of either party to enforce at any
time the provisions hereof shall not be construed to be a waiver of such
provisions nor of the right of such party thereafter to enforce each and every
such provision.


                                      -12-
<PAGE>   13
         13.4 Arbitration. The parties agree to submit any dispute they are
unable to resolve between them to binding arbitration by a single arbitrator in
Santa Clara, California, in accordance with the rules of the American
Arbitration Association.

         13.5 Force Majeure. Neither party shall be liable to the other party
for any delay or omission in the performance of any obligation under this
Agreement where the delay or omission is due to any cause or condition beyond
the reasonable control of the party obliged to perform, including, but not
limited to, strikes or other labor difficulties, acts of God, earthquakes, acts
of government (including but not limited to the refusal to issue necessary
import or export licenses), war, riots, embargoes, or inability to obtain
supplies ("Force Majeure"). If Force Majeure prevents or delays the performance
by a party of any obligation under this Agreement, then the party claiming Force
Majeure shall promptly notify the other party thereof in writing. In the event
that Force Majeure shall continue for a period greater than ninety (90) days,
either party may terminate the Agreement.

         13.6 Entire Agreement. This Agreement contains the entire understanding
of the parties with respect to the matters herein contained, supersedes all
prior understandings between the parties with respect to the distribution of the
Products, and may from time to time be changed, but only by an instrument in
writing signed by both parties.

         13.7 Counterparts. This Agreement may be executed in any number of
counterparts, each of which when so executed and delivered shall be deemed an
original and all of which taken together shall constitute but one and the same
instrument.


         IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date first above written.

COLLAGEN CORPORATION                                TISSUE TECHNOLOGIES, INC.


By:         /s/ David Foster                        By:      /s/ Jesse Kramer
            ----------------                                 ----------------
Name:       David Foster                            Name:    Jesse Kramer
            ------------                                     ------------
Title:  Vice President and Chief Financial Officer  Title:   President
        ------------------------------------------           ---------


                                      -13-
<PAGE>   14
                                   SCHEDULE A

                       Description of Products and Prices


1.0 Description of Products The Supplier's existing biocompatible tubular E-PTFE
product(s) for soft tissue augmentation and management of facial wrinkles, as
well as any and all additional and/or improved biocompatible implant product(s)
for soft tissue augmentation and management of facial wrinkles made by the
Supplier, or by third parties to the Supplier's benefit, during the term of this
Agreement. Such product(s), as well as any and all additional and/or improved
biocompatible product(s) shall be limited to any product covered by the claims
of a patent application or issued patent included in the Intellectual Property
Rights.

A single unit ("unit(s)") of the first such tubular E-PTFE product shall consist
*** , packaged and labeled in a sterile and FDA-approved manner.

Future Products will be defined and mutually agreed upon prior to regulatory
approval in any given country.

2.0      Purchase Price

         2.1 During the Initial Period the Supplier shall sell units of the
Product(s) to the Distributor at the agreed upon price of *** .

         2.2 Subsequent to the Initial Period, the purchase price for Product(s)
shall be based and calculated as *** .

<TABLE>
<CAPTION>
Year    Percentage of net sales to Distributor    Percentage of net sales to Supplier
-------------------------------------------------------------------------------------
<S>           <C>                                     <C>        
4              *** %                                  *** %
5              *** %                                  *** %
6              *** %                                  *** %
7              *** %                                  *** %
8              *** %                                  *** %
9              *** %                                  *** %
10             *** %                                  *** %
</TABLE>

--------------------
***Confidential treatment requested


                                      -14-
<PAGE>   15
                                   SCHEDULE B

                                    Territory

1.0      Territory.

         1.1      The United States of America

         1.2      The European Economic Area

         1.3      All other countries of the world.


                                      -15-
<PAGE>   16
                                   SCHEDULE C

1.0      Minimum Purchases

In accordance with Sections 4.3 and 5.9 of the Worldwide Medical Product
Distribution Agreement, Distributor agrees to the minimum purchase requirements
set forth below.


1.1      For the Initial Period:

<TABLE>
<CAPTION>
Year        Minimum Purchases in US dollars           Minimum Purchases in units  (***/unit)
--------------------------------------------------------------------------------------------------
<CAPTION>
<S>             <C>                                           <C>    
1               $500,000                                       ***
2               $750,000                                       ***
3               $1,250,000                                     ***
</TABLE>

1.2         Subsequent to the Initial Period:

<TABLE>
<CAPTION>
Year              Minimum Purchases in US dollars                 Purchase increase from prior year
---------------------------------------------------------------------------------------------------
<S>               <C>                                                  <C>
4                 $1,437,500                                           ***  %
5                 $1,653,125                                           ***  %
6                 ***                                                  ***  %
7                 ***                                                  ***  %
8                 ***                                                  ***  %
9                 ***                                                  ***  %
10                ***                                                  ***  %
</TABLE>

--------------------
***Confidential treatment requested


                                      -16-
<PAGE>   17
                                   SCHEDULE D


1.0      Delivery Sites

         1.1 Supplier shall ship Products to Distributor, in accordance with
Distributor's instructions included with any purchase order, to the following
destinations:

         (a)      Within the United States to:
                  Collagen Corporation
                  48490 Milmont Drive
                  Fremont, CA  94538

                  The minimum quantity to be shipped to this destination is: ***
                  units


         (b)      For CE marked products to:

                  Collagen Corporation
                  48490 Milmont Drive
                  Fremont, CA  94538

                  OR

                  Other designated site in the European Economic Area (EEA).

                  The minimum quantity to be shipped to these destinations is:
                  *** units


         (c)      For non-CE marked products to all other countries of the world
                  to:

                  A designated site, to be determined, in one or more country
                  other than the United States or EEA.

                  The minimum quantity to be shipped to this destination is: ***
                  units


                                      -17-
<PAGE>   18
                                    EXHIBIT A

                   University of California License Agreement












                                      -18-
<PAGE>   19


                          EXCLUSIVE LICENSE AGREEMENT

                                    between

                  THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

                                      and

                           TISSUE TECHNOLOGIES, INC.

                                      for

                   PERMANENT SOFT TISSUE AUGMENTATION SYSTEM

                             U.C. CASE NO. 93-057-1

<PAGE>   20
                               TABLE OF CONTENTS

<TABLE>
<S>                                                                          <C>
BACKGROUND.................................................................   1

 1.  DEFINITIONS...........................................................   2

 2.  LIFE OF PATENT EXCLUSIVE GRANT........................................   4

 3.  SUBLICENSES...........................................................   4

 4.  LICENSE ISSUE FEE.....................................................   5

 5.  ROYALTIES.............................................................   6

 6.  DUE DILIGENCE.........................................................   9

 7.  PROGRESS AND ROYALTY REPORTS..........................................  14

 8.  BOOKS AND RECORDS.....................................................  15

 9.  LIFE OF THE AGREEMENT.................................................  16

10.  TERMINATION BY THE REGENTS............................................  16

11.  TERMINATION BY LICENSEE...............................................  17

12.  DISPOSITION OF LICENSED PRODUCTS ON HAND UPON 
     TERMINATION...........................................................  17

13.  USE OF NAMES, TRADEMARKS, AND CONFIDENTIALITY.........................  18

14.  LIMITED WARRANTY......................................................  19

15.  PATENT PROSECUTION AND MAINTENANCE....................................  20

16.  PATENT MARKING........................................................  22

17.  PATENT INFRINGEMENT...................................................  22

18.  INDEMNIFICATION.......................................................  24

19.  NOTICES...............................................................  25

20.  ASSIGNABILITY.........................................................  26
</TABLE>
<PAGE>   21
<TABLE>
<S>                                                                          <C>
21.  LATE PAYMENTS..........................................................  26

22.  WAIVER.................................................................  27

23.  FAILURE TO PERFORM.....................................................  27

24.  GOVERNING LAWS.........................................................  27

25.  FOREIGN GOVERNMENT APPROVAL OR REGISTRATION............................  27

26.  EXPORT CONTROL LAWS....................................................  28

27.  FORCE MAJEURE..........................................................  28

28.  CONFIDENTIAL INFORMATION...............................................  28

29.  MISCELLANEOUS..........................................................  29
</TABLE>

 
<PAGE>   22
UC Case No. 93-057-1

                          EXCLUSIVE LICENSE AGREEMENT

                                      for

                   PERMANENT SOFT TISSUE AUGMENTATION SYSTEM

        THIS LICENSE AGREEMENT, the "Agreement", is made and is effective
December 1, 1993, by and between THE REGENTS OF THE UNIVERSITY OF CALIFORNIA, a
California corporation having its statewide administrative offices at 300
Lakeside Drive, 22nd Floor, Oakland, California 94612-3550, hereinafter
referred to as "The Regents", and TISSUE TECHNOLOGIES, INC. a California
corporation having a principal place of business at 1372 Green Street, San
Francisco, California 94109, hereinafter referred to as the "Licensee."

                                   BACKGROUND

        Certain inventions, generally characterized as Permanent Soft Tissue
Augmentation System, hereinafter collectively referred to as the "Invention,"
were made in the course of research at the University of California, San
Francisco by Drs. Robert Schindler and Corey Maas and are covered by Regents'
Patent Rights as defined below.

        The Licensee entered into a Letter of Intent (U.C. Control No.
93-30-0385) with

                                       1
<PAGE>   23
The Regents, effective June 14, 1993 and terminating on December 31, 1993, for
the purpose of declaring the mutual intention of the parties to negotiate with
each other for an exclusive license on the Invention.

        The Licensee is a "small business firm" as defined in 15 U.S.C. 632.

        The Licensee is desirous of obtaining certain rights from The Regents
for the commercial development, manufacture, use, and sale of the Invention,
and The Regents is willing to grant such rights.

        The Regents is desirous that the Invention be developed and utilized to
the fullest extent so that the benefits can be enjoyed by the general public.

Both parties recognize and agree that royalties due hereunder will be paid on
both pending patent applications and issued patents.

        Both parties agree as follows:

                                 1. DEFINITIONS

        1.1 "Regents' Patent Rights" means patent rights to any subject matter
claimed in or covered by any of the following: pending U.S. Patent Application
serial no. 08/090,518, entitled Soft Tissue Augmentation Apparatus, filed July
12, 1993, by Drs. Robert Schindler and Corey Maas and assigned to The Regents;
and continuing applications thereof including divisions and substitutions but
including continuation-in-part applications only to the extent that the claim
was supported in the original disclosure; any patents issuing on said
application or continuing applications including reissues; and any
corresponding foreign applications or patents.

        1.2 "Regents' Proprietary Rights" means information related to the
Invention, 

                                       2
<PAGE>   24
including data, drawings and sketches, designs, test results, Data as defined in
Article 28, Confidential Information, and information of a like nature, whether
patentable or not, developed by Drs. Robert Schindler and Corey Maas of the
University of California San Francisco.

        1.3     "Licensed Product" means any material that is either covered by
Regents' Patent Rights or Regents' Proprietary Rights or whose manufacture,
use, or sale would constitute, but for the license granted to the Licensee
pursuant to this Agreement, an infringement of any pending or issued claim
within Regents' Patent Rights.

        1.4     "Licensed Method" means any method that is covered by Regents'
Patent Rights or Regents' Proprietary Rights or whose use or practice would
constitute, but for the license granted to the Licensee pursuant to this
Agreement, an infringement of any claim within Regents' Patent Rights.

        1.5     "Net Sales" means the total of the gross invoice prices of
Licensed Products less the sum of the following actual and customary deductions
where applicable: cash, trade, or quantity discounts; sales, use, tariff,
import/export duties, or other excise taxes imposed upon particular sales;
transportation charges and allowances or credits to customers because of
rejections or returns.

        1.6     "Affiliate" means any corporation or other business entity in
which Licensee owns or controls, directly or indirectly, at least fifty percent
(50%) of the outstanding stock or other voting rights entitled to elect
directors; provided, however, that in any country where the local law shall not
permit foreign equity participation of at least 50%, then an "Affiliate" shall
include any company in which Licensee shall own or control, directly or
indirectly, the maximum percentage of such outstanding stock or voting rights
permitted by local law.

                                       3
<PAGE>   25
        1.7 "Joint Venture" means any entity established pursuant to an
agreement between a third party (or parties) and Licensee to carry out a
business enterprise.

                       2. LIFE OF PATENT EXCLUSIVE GRANT

        2.1 Subject to the limitations set forth in this Agreement, The Regents
hereby grants to Licensee a (worldwide) license under Regents' Patent Rights
and Regents' Proprietary Rights to make, have made, use, and sell Licensed
Products and to practice the Licensed Method.

        2.2 Except as otherwise provided herein, the license granted in section
2.1 shall be exclusive for the life of the Agreement.

        2.3 The Regents expressly reserves the right to use the Invention and
associated technology for educational and research purposes.

                                 3. SUBLICENSES
        
        3.1 The Regents also grants to Licensee the right to issue sublicenses
to third parties to make, have made, use and sell Licensed Products and to
practice the Licensed Method provided Licensee has current exclusive rights
thereto under this Agreement. To the extent applicable, such sublicenses shall
include all of the rights of and obligations due to The Regents that are
contained in this Agreement.

        3.2 Licensee shall provide The Regents with a copy of each sublicense
issued hereunder; collect and guarantee payment of all royalties due The
Regents from sublicensees; and summarize and deliver all reports due The
Regents from sublicensees.

        3.3 Upon termination of this Agreement for any reason, The Regents, at
its sole

                                       4
<PAGE>   26
                                   APPENDIX A

discretion, shall determine whether any or all sublicenses shall be canceled or
assigned to The Regents.

                              4. LICENSE ISSUE FEE

        4.1 Licensee agrees to pay to The Regents a License Issue Fee of 
[ *** ] according to the following schedule:

          - [ *** ] to be paid within [ *** ] after the execution date of this 
            Agreement

          - [ *** ] to be paid upon submission of Product Market Approval
            (PMA) or 510K data to the U.S. Food and Drug Administration (FDA),
            but no later than [ *** ] 

          - [ *** ] to be paid on [ *** ] and 

          - [ *** ] to be paid upon FDA marketing approval, but no later than
            [ *** ]

        4.2 This license issue fee is non-refundable, non-cancellable, and not
an advance against royalties.


*** Confidential treatment requested

                                       5
<PAGE>   27
                                  5. ROYALTIES

        5.1 Licensee shall also pay to The Regents an earned royalty of [ *** ]
of the Net Sales of Licensed Products. In the event the last patent application
under this Agreement is abandoned and no patent in Regents' Patent Rights has
issued, Licensee shall pay to The Regents an earned royalty of [ *** ] in the
first full year of commercial sales of Licensed Products covered by Regent's
Proprietary Rights following such abandonment, [ *** ] in the second full year
of such commercial sales following such abandonment, [ *** ] in the third full
year of such commercial sales following such abandonment, [ *** ] in the fourth
year of such commercial sales following such abandonment, and no earned royalty
in subsequent years.

        5.2 For sales of Licensed Products to an Affiliate or Joint Venture
from Licensee at a reduced price from that customarily charged to an unrelated
third party, the royalty paid to The Regents shall be based on the Net Sales of
Licensed Products of the Affiliate or Joint Venture to the Affiliate's or Joint
Venture's customers. Where Licensee transfers Licensed Products for end-use to
itself or an Affiliate or Joint Venture, such transfer shall be considered a
sale at list price, and The Regents shall be entitled to receive a royalty
thereon in accordance with this Article 5, (ROYALTIES). Each reference to
Licensee herein shall be meant to include its Affiliates and Joint Ventures.

        5.3 Paragraphs 1.1, 1.2, 1.3, and 1.4 define Regents' Patent Rights,
Licensed Products, and Licensed Methods so that royalties shall be payable on
products and methods covered by both pending patent applications and issued
patents as well as on products and methods covered by Regents' Proprietary
Rights. Earned royalties shall accrue in each country for the 

***Confidential treatment requested

                                       6
<PAGE>   28
duration of Regents' Patent Rights in that country and shall be payable to The
Regents when Licensed Products are invoiced, or if not invoiced, when delivered
to a third party. In the event the last patent application under this Agreement
in that country is abandoned and no patent in Regents' Patent Rights has issued
for that country then Licensee shall pay to The Regents an earned royalty based
on sales of Licensed Products covered by The Regents' Proprietary Rights in
that country as provided in paragraph 5.1.

        5.4     Royalties accruing to The Regents shall be paid to The Regents 
[ *** ] on or before the following dates [ *** ]:

                                    [ *** ]

                                    [ *** ]

                                    [ *** ]

                                    [ *** ]

Each such payment will be for royalties which accrued within the Licensee's
most recently completed [ *** ].

        5.5     Licensee shall pay to The Regents a minimum annual royalty of 
[ *** ] and [ *** ] thereafter, beginning with the calendar year [ *** ]. This
minimum annual royalty shall be paid to The Regents by [ *** ] of each year and 
shall be credited against the earned royalty (if any) due and owing for the 
calendar year in which the minimum payment was made.

        5.6     Notwithstanding the minimum royalties stated in paragraph 5.5
(Minimum Royalties), in the event the last patent application under this
Agreement is abandoned and no patent in Regents' Patent Rights has issued,
Licensee shall pay to The Regents a minimum annual royalty

*** confidential treatment requested

                                       7

<PAGE>   29
equal to [ *** ] of the minimum royalty stipulated for that year in paragraph
5.5 for the first year of commercial sales following such abandonment, [ *** ]
of the minimum royalty stipulated for that year in paragraph 5.5 for the second
full year of such commercial sales following such abandonment, [ *** ] of the
minimum royalty stipulated for that year in paragraph 5.5 for the third full
year of such commercial sales following such abandonment, [ *** ] of the
minimum royalty stipulated for that year in paragraph 5.5 for the fourth year of
such commercial sales following such abandonment, and no minimum annual royalty
in subsequent years.

        5.7     All monies due The Regents shall be payable in United States
funds collectible at par in San Francisco, California. When Licensed Products
are sold for monies other than United States dollars, the earned royalties will
first be determined in the foreign currency of the country in which such
Licensed Products were sold and then converted into equivalent United States
funds. The exchange rate will be that rate quoted in the Wall Street Journal on
the last business day of the reporting period.

        5.8     Royalties earned with respect to sales occurring in any country
outside the United States shall not be reduced by any taxes, fees, or other
charges imposed by the government of such country on the remittance of royalty
income. The Licensee shall also be responsible for all bank transfer charges.
Notwithstanding this, all payments made by the Licensee in fulfillment of The
Regents' tax liability in any particular country shall be credited against
Earned Royalties, royalties, or fees due The Regents for that country.

        5.9     If at any time legal restrictions prevent the prompt remittance
of part or all royalties by the Licensee with respect to any country where a
Licensed Product is sold, the

*** confidential treatment requested


                                       8
<PAGE>   30
Licensee shall pay such royalties to The Regents from the Licensee's United
States source of funds.

        5.10 In the event that any patent or any claim thereof included within
the Regents' Patent Rights shall be held invalid in a final decision by a court
of competent jurisdiction and last resort and from which no appeal has or can
be taken, all obligation to pay royalties based on such patent or claim or any
claim patentably indistinct therefrom shall cease as of the date of such final
decision. The Licensee shall not, however, be relieved from paying any
royalties that accrued before such decision or that are based on another patent
or claim not involved in such decision or that are based on the Regents'
Proprietary Rights.

                                6. DUE DILIGENCE

        6.1 The Licensee, upon execution of this Agreement, shall diligently
proceed with the development, manufacture, and sale of Licensed Products and
shall earnestly and diligently endeavor to market the same within a reasonable
time after execution of this Agreement and in quantities sufficient to meet the
market demands therefor.

        6.2 The Licensee shall be entitled to exercise prudent and reasonable
business judgment in meeting its due diligence obligations hereunder.

        6.3 The Licensee shall endeavor to obtain all necessary governmental
approvals for the manufacture, use, and sale of Licensed Products.

        6.4 If the Licensee is unable to perform any of the following:

        6.4.1 initiate a pilot animal study for the device by [ *** ]; or

        6.4.2 complete the pilot animal study for the device and, if it is
necessary for

*** confidential treatment requested


                                       9
<PAGE>   31
              government approval, initiate a full animal study for the device
              by December 31, 1994; or

        6.4.3 submit a 510K covering Licensed Products to the United States FDA
              by [ *** ]; or  

        6.4.4 initiate human trials on the device and complete the full animal
              study on the device by [ *** ]; or

        6.4.5 market Licensed Products in the United States within [ *** ] of
              receiving approval of such Licensed Product's 510K or PMA from
              the U.S. FDA; or 

        6.4.6 reasonably fill the market demand for Licensed Products following
              commencement of marketing at any time during the exclusive period
              of this Agreement; 

then The Regents shall have the right and option either to terminate this
Agreement or to reduce the Licensee's exclusive license to a nonexclusive
license. This right, if exercised by The Regents, supersedes the rights granted
in Article 2 (GRANT).

        6.5 In addition to the obligations set forth above, the Licensee shall
spend an aggregate of not less than [ *** ] for the development and
commercialization of Licensed Products during the first 3 years of this
Agreement according to the following schedule:

        1994 [ *** ]

        1995 [ *** ]

        1996 [ *** ]


*** confidential treatment requested

                                       10

<PAGE>   32
        6.6     Either party to this Agreement may refer a dispute arising
under this Article 6 (DUE DILIGENCE) to arbitration. Such referral to
arbitration shall be made by so notifying the other party in writing in
accordance with the provisions of Article 19 hereto (NOTICES), stating the
nature of the dispute to be resolved. Any such arbitration shall be controlled
by the provisions of this Article 6.

        6.7     Within fifteen (15) business days following such notice, three
arbitrators shall be selected by the following process:

        6.7.1   Each Party shall designate one individual, not an employee,
                director, or shareholder of the Party or sublicensee of the
                Party, to serve as an arbitrator.

        6.7.2   These arbitrators shall select a third individual who shall be
                an attorney experienced in arbitration proceedings to serve as
                the third arbitrator and to preside in resolution of the
                dispute. The third arbitrator shall not be an employee,
                director, or shareholder of either Party or sublicensee of
                either Party.

        6.8     Within five (5) business days after selection, the arbitrators
shall meet with the Parties at which time the Parties shall each present in
writing the issue to be resolved and a proposed ruling on it. Such writing
shall be served on the other Party in advance and shall be limited to no more
than twenty (20) pages.

        6.9     The following general provisions shall apply to the
arbitration proceeding:

        6.9.1   No later than thirty (30) days after the appointment of the
third arbitrator, the arbitrators shall set a date for a hearing to resolve the
issue identified by the Parties.  The hearing shall take place no later than
one hundred twenty (120)


                                       11
<PAGE>   33
        days from the original notice to arbitrate.

6.9.2   The arbitrators shall permit the taking of no more than one (1)
        deposition by each Party, and shall permit, subject to the provisions of
        a mutually agreeable protective order, the production of only those
        documents immediately and directly bearing on the issue or issues
        subject to arbitration and only to the extent necessary for the
        convenience and use of the arbitrators, and shall not require or permit
        any other discovery by any means, including, but not limited to,
        depositions, interrogatories, or production of documents.


6.9.3   No later than ten (10) business days prior to the hearing, each Party
        may submit a single written brief or memorandum in support of its
        position which may be no more than twenty (20) pages. Each Party shall
        be entitled to no more than three (3) hours of hearing to present
        testimony or documentary evidence. Such time limitation shall include
        any direct, cross, or rebuttal testimony, but such time limitation shall
        only be charged against the Party conducting such direct, cross, or
        rebuttal testimony. It shall be the responsibility of the arbitrators to
        determine whether each Party has had the three (3) hours to which it is
        entitled or may, upon good cause shown, have additional time to present
        its case.

6.9.4   Each Party shall have the right to be represented by counsel. The
        arbitrators shall have sole discretion with regard to the admissability
        of evidence. Admissibility will be decided by two-thirds vote.


                                       12

<PAGE>   34
        6.9.5 Within fifteen (15) days of the conclusion of the hearing, each
Party must submit a proposed finding to the arbitrators.

        6.10 The arbitrators shall rule on the disputed issue within thirty
(30) days following the completion of the testimony of both Parties. Such
ruling shall encompass in its entirety the proposed findings of one of the
Parties on the disputed issue. The issue shall be resolved upon two-thirds vote
of the arbitrators.

        6.11 Arbitration shall take place in the location of choice of the
party who has not requested arbitration. All hearing costs for a hearing shall
be shared equally between the Parties.

        6.12 The arbitrators shall be paid reasonable fees plus expenses, which
fees and expenses shall be shared equally by the Parties.

        6.13 The decision of the arbitrators shall be enforceable but not
appealable in any court of competent jurisdiction.

        6.14 To exercise either the right to terminate this Agreement or to
reduce the license to a nonexclusive license for lack of diligence, The Regents
must give the Licensee written notice of the deficiency. The Licensee
thereafter has sixty (60) days to cure the deficiency or to request
arbitration. If The Regents has not received a written request for arbitration
or satisfactory tangible evidence that the deficiency has been cured by the end
of the sixty (60)-day period, then The Regents may, at its option, either
terminate this Agreement or reduce the Licensee's exclusive license to a
nonexclusive license by giving written notice to the Licensee. These notices
shall be subject to Article 19 (NOTICES).

                                       13
<PAGE>   35
                        7.  PROGRESS AND ROYALTY REPORTS

        7.1     [ *** ] and [ *** ] thereafter, the Licensee shall submit to
The Regents a progress report covering the Licensee's activities related to the
development and testing of all Licensed Products and the obtaining of the
governmental approvals necessary for marketing. These progress reports shall be
made for each Licensed Product until the first commercial sale of that Licensed
Product occurs in the United States.

        7.2     The progress reports submitted under section 7.1 should
include, but not be limited to, the following topics:

    -   summary of work completed including results of clinical trials

    -   key scientific discoveries

    -   summary of work in progress

    -   current schedule of anticipated events or milestones

    -   market plans for introduction of Licensed Products, and

    -   a summary of resources (dollar value) spent in the reporting period

        7.3     The Licensee shall have a continuing responsibility to keep The
Regents informed of the large/small entity status (as defined by the United
States Patent and Trademark Office) of itself and its sublicensees and
Affiliates.

        7.4     The Licensee also agrees to report to The Regents in its
immediately subsequent progress and royalty report the date of first commercial
sale of a Licensed Product in each country.

        7.5     After the first commercial sale of a Licensed Product anywhere
in the world, the Licensee will make [ *** ] royalty reports to The Regents on
or before [ *** ]

*** confidential treatment requested

                                       14
<PAGE>   36

Each such royalty report will cover the Licensee's most recently completed
[ * * * ] and will show: (a) the gross sales and Net Sales of Licensed Products
sold by the Licensee during the most recently completed calendar quarter, (b)
the number of each type of Licensed Product sold, (c) the royalties, in U.S.
dollars, payable hereunder with respect to such sales, (d) the method used to
calculate the royalty, and (e) the exchange rates used.

        7.6  If no sales of Licensed Products have been made during any
reporting period, a statement to this effect shall be required.


                             8.  BOOKS AND RECORDS

        8.1  The Licensee shall keep books and records accurately showing all
Licensed Products manufactured, used, and/or sold under the terms of this
Agreement. Such books and records shall be preserved for at least five (5)
years from the date of the royalty payment to which they pertain and shall be
open to inspection by representatives or agents of The Regents at reasonable
times.

        8.2  The fees and expenses of The Regents' representatives performing
such an examination shall be borne by The Regents. However, if an error in
royalties of more than five percent (5%) of the total royalties due for any
year is discovered, then the fees and expenses of these representatives shall
be borne by the Licensee.


* * * Confidential treatment requested


                                       15

<PAGE>   37

                           9.  LIFE OF THE AGREEMENT

        9.1  Unless otherwise terminated by operation of law or by acts of the
parties in accordance with the terms of this Agreement, this Agreement shall be
in force from the effective date recited on page one and shall remain in effect
for the life of the last-to-expire patent licensed under this Agreement, or for
twenty (20) years from the effective date of this Agreement if no patent
issues, or until the last patent application licensed under this Agreement is
abandoned and no patent in Regents' Patent Rights ever issues.

        9.2  Any termination of this Agreement shall not affect the rights and
obligations set forth in the following Articles:

        Article 8     Books and Records

        Article 12    Disposition of Licensed Products on Hand Upon Termination

        Article 13    Use of Names, Trademarks, and Confidentiality

        Article 18    Indemnification

        Article 23    Failure to Perform

        Article 28    Confidential Information


                        10.  TERMINATION BY THE REGENTS

        10.1  If the Licensee should violate or fail to perform any term or
covenant of this Agreement, then The Regents may give written notice of such
default (Notice of Default) to the Licensee. If the Licensee should fail to
repair such default within sixty (60) days of the effective date of such
notice, The Regents shall have the right to terminate this Agreement and the
licenses herein by a second written notice (Notice of Termination) to the
Licensee. If a Notice of


                                       16

<PAGE>   38
Termination is sent to the Licensee, this Agreement shall automatically
terminate on the effective date of such notice. Such termination shall not
relieve the Licensee of its obligation to pay any royalty or license fees owing
at the time of such termination and shall not impair any accrued right of The
Regents. These notices shall be subject to Article 19 (Notices).

                          11.  TERMINATION BY LICENSEE

        11.1    The Licensee shall have the right at any time to terminate this
Agreement in whole or as to any portion of Regents' Patent Rights by giving
notice in writing to The Regents. Such notice of termination shall be subject
to Article 19 (Notices), and termination of this Agreement shall be effective
ninety (90) days from the effective date of such notice.

        11.2    Any termination pursuant to the above paragraph shall not
relieve the Licensee of any obligation of liability accrued hereunder prior to
such termination or rescind anything done by the Licensee or any payments made
to The Regents hereunder prior to the time such termination becomes effective,
and such termination shall not affect in any manner any rights of The Regents
arising under this Agreement prior to such termination. Any unpaid part of the
License Issue Fee of paragraph 4.1 becomes due and payable at the time of
termination by Licensee.

         12.  DISPOSITION OF LICENSED PRODUCTS ON HAND UPON TERMINATION

        12.1    Upon termination of this Agreement, the Licensee shall have the
privilege of disposing of all previously made or partially made Licensed
Products, but no more, within a period of one hundred and twenty (120) days
provided, however, that the sale of such Licensed Products 


                                       17
<PAGE>   39
shall be subject to the terms of this Agreement including, but not limited to,
the payment of royalties at the rate and at the time provided herein and the
rendering of reports thereon.

              13.  USE OF NAMES, TRADEMARKS, AND CONFIDENTIALITY

        13.1    Nothing contained in this Agreement shall be construed as
conferring any right to use in advertising, publicity, or other promotional
activities any name, trade name, trademark, or other designation of either
party hereto (including contraction, abbreviation, or simulation of any of the
foregoing). Unless required by law, the use by the Licensee of the name "The
Regents of the University of California" or the use by the Licensee of the name
of any campus of the University of California is expressly prohibited.

        13.2    Neither The Regents nor Licensee shall be free to release the
terms and conditions of this Agreement to third parties unless required by law
without the written consent of the other.

        13.3    Notwithstanding paragraph 13.2, it is understood that The 
Regents shall be free to release to the inventors and senior administrative 
officials employed by The Regents the terms and conditions of this Agreement
upon their request. If such release is made, The Regents shall request that
such terms and conditions not be disclosed to others. It is further understood
that should a third party inquire whether a license to Regents' Patent Rights
is available, The Regents may disclose the existence of this Agreement and the
Extent of the grant in Article 2 (GRANTS) to such third party, but shall not
disclose the name of the Licensee except where The Regents is required to
release such information under either the California Public Records Act or
other applicable law.

                                       18
<PAGE>   40
        13.4    Notwithstanding the requirements for confidentiality contained
within this Article 13, The Regents hereby authorizes the Licensee to include
in any NDA for a Licensed Product a list of patents included within Regents'
Patent Rights identifying The Regents as patent owner.

                             14.  LIMITED WARRANTY

        14.1    The Regents warrants to the Licensee that it has the lawful
right to grant this license.

        14.2    This license and the associated Invention are provided WITHOUT
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR ANY OTHER
WARRANTY, EXPRESSED OR IMPLIED. THE REGENTS MAKES NO REPRESENTATION OR WARRANTY
THAT THE LICENSED PRODUCTS OR LICENSED METHODS WILL NOT INFRINGE ANY PATENT OR
OTHER PROPRIETARY RIGHT.

        14.3    IN NO EVENT WILL THE REGENTS BE LIABLE FOR ANY INCIDENTAL,
SPECIAL, OR CONSEQUENTIAL DAMAGES RESULTING FROM EXERCISE OF THIS LICENSE OR
THE USE OF THE INVENTION OR LICENSED PRODUCTS.

        14.4    Nothing in this Agreement shall be construed as:

        (14.4.1)        a warranty or representation by The Regents as to the
                        validity or scope of any Regents' Patent Rights; or

        (14.4.2)        a warranty or representation that anything made, used,
                        sold, or otherwise disposed of under any license granted
                        in this Agreement is


                                       19

<PAGE>   41
                 or will be free from infringement of patents of third parties; 
                 or

        (14.4.3) an obligation to bring or prosecute actions or suits against
                 third parties for patent infringement except as provided in 
                 Article 17 (PATENT INFRINGEMENT); or

        (14.4.4) conferring by implication, estoppel, or otherwise any license
                 or rights under any patents of The Regents other than Regents' 
                 Patent Rights as defined herein, regardless of whether such 
                 patents are dominant or subordinate to Regent's Patent Rights; 
                 or

        (14.4.5) an obligation to furnish any know-how not provided in Regents'
                 Patent Rights.

                     15. PATENT PROSECUTION AND MAINTENANCE

        15.1 Provided that Licensee has paid billings and rebillings as
provided for in paragraph 15.4, The Regents shall diligently prosecute and
maintain the United States patents comprising Regents' Patent Rights using
counsel of its choice. The Regents' counsel will take instructions only from
The Regents. The Regents shall provide the Licensee with copies of all relevant
documentation so that the Licensee may be informed and apprised of the
continuing prosecution. The Licensee agrees to keep this documentation
confidential. 

        15.2 The Regents shall use all reasonable efforts to amend any patent
application to include claims reasonably requested by the Licensee to protect
the products contemplated to be sold under this Agreement.

        15.3 Licensee shall apply for an extension of the term of any patent
included within 

                                       20
<PAGE>   42
Regents' Patent Rights if appropriate under the Drug Price Competition and
Patent Term Restoration Act of 1984 and/or European, Japanese, and other
foreign counterparts of this law. The Licensee shall prepare all such
documents, and The Regents agrees to execute such documents and to take such
additional action as the Licensee may reasonably request in connection
therewith. 

        15.4 The costs of preparing, filing, prosecuting, and maintaining all
United States patent applications and/or patents contemplated by this Agreement
shall be borne by Licensee. This includes patent prosecution costs for this
Invention incurred by The Regents prior to the execution of this Agreement.
Such prior costs (approximately $8,611.71 as of September 30, 1993) will be due
within thirty (30) days of the execution of this Agreement. Current and future
costs for patent prosecution and maintenance will be billed to the Licensee by
The Regents as incurred and shall be payable within thirty (30) days of the
billing date.

        15.5 The Licensee shall have the right to request The Regents to obtain
patent protection on the Invention in foreign countries if available and if it
so desires. The Licensee must notify The Regents within seven (7) months of the
filing of the corresponding United States application of its decision to obtain
foreign patents. This notice concerning foreign filing shall be in writing,
must identify the countries desired, and reaffirm Licensee's obligation to
underwrite the costs thereof. The absence of such a notice from the Licensee to
The Regents shall be considered an election not to secure foreign rights.

        15.6 The preparation, filing, and prosecuting of all foreign patent
applications filed at the Licensee's request, as well as the maintenance of all
resulting patents, shall be at the sole expense of the Licensee. Such patents
shall be held in the name of the Regents and shall be obtained using counsel of
The Regents' choice.

                                       21
<PAGE>   43
        15.7 The Licensee's obligation to underwrite and to pay patent
prosecution costs shall continue for so long as this Agreement remains in
effect provided, however, that the Licensee may terminate its obligations with
respect to any given patent application or patent upon three (3) months written
notice to The Regents. The Regents will use its best efforts to curtail patent
costs when such a notice is received from the Licensee. Those costs which
cannot be curtailed will be due and owing when rebilled. The Regents may
continue prosecution and/or maintenance of such application(s) or patent(s) at
its sole discretion and expense provided, however, that the Licensee shall have
no further right or licenses thereunder.

        15.8 The Regents shall have the right to file, prosecute, or maintain 
patent applications at its own expense in any country in which the Licensee has
not elected to file, prosecute, or maintain patent rights in accordance with
this Article 15, and such applications and resultant patents shall not be
subject to this Agreement.

                               16. PATENT MARKING

        16.1 The Licensee agrees to mark all Licensed Products made, used, or
sold under the terms of this Agreement, or their containers, in accordance with
the applicable patent marking laws.

                            17. PATENT INFRINGEMENT

        17.1 In the event that the Licensee shall learn of the substantial
infringement of any patent or patent extension licensed under this Agreement,
the Licensee shall call The Regents' attention thereto in writing and shall
provide The Regents with reasonable evidence of such

                                       22
 
<PAGE>   44
infringement. Both parties to this Agreement agree that during the period and
in a jurisdiction where the Licensee has exclusive rights under this Agreement,
neither will notify a third party of the infringement of any of Regents' Patent
Rights without first obtaining consent of the other party, which consent shall
not be unreasonably denied. Both parties shall use their best efforts in
cooperation with each other to terminate such infringement without litigation.

        17.2 The Licensee may request that The Regents take legal action
against the infringement of Regents' Patent Rights. Such request shall be made
in writing and shall include reasonable evidence of such infringement and
damages to the Licensee. If the infringing activity has not been abated within
ninety (90) days following the effective date of such request, The Regents
shall have the right to:

             a) commence suit on its own account or

             b) refuse to participate in such suit,

and The Regents shall give notice of its election in writing to the Licensee by
the end of the one-hundredth (100th) day after receiving notice of such request
from the Licensee. The Licensee may thereafter bring suit for patent
infringement if and only if The Regents elects not to commence suit and if the
infringement occurred during the period and in a jurisdiction where the
Licensee had exclusive rights under this Agreement. However, in the event the
Licensee elects to bring suit in accordance with this paragraph, The Regents
may thereafter join such suit at its own expense.

        17.3 Such legal action as is decided upon shall be at the expense of
the party on account of whom suit is brought and all recoveries recovered
thereby shall belong to such party provided, however, that legal action brought
jointly by The Regents and the Licensee and fully

                                       23
<PAGE>   45
participated in by both shall be at the joint expense of the parties and all
recoveries shall be shared jointly by them in proportion to the share of
expense paid by each party.

        17.4    Each party agrees to cooperate with the other in litigation
proceedings instituted hereunder but at the expense of the party on account of
whom suit is brought. Such litigation shall be controlled by the party bringing
the suit except that The Regents may be represented by counsel of its choice
pursuant to The Regents' determination in any suit brought by the Licensee.

                              18.  INDEMNIFICATION

        18.1    The Licensee agrees to indemnify, hold harmless, and defend The
Regents, their officers, employees, and agents; the sponsors of the research
that led to the Invention; and the inventors of the patents and patent
applications in Regents' Patent Rights and their employers against any and all
claims, suits, losses, damage, costs, fees, and expenses resulting from or
arising out of exercise of this license or any sublicense. This indemnification
will include, but will not be limited to, any product liability.

        18.2    The Licensee, at its sole cost and expense, shall insure its
activities in connection with the work under this Agreement, and before
Licensee conducts any non-financial commercialization activities concerning the
Licensed Products outside of development and trials performed at the University
of California by employees of the University of California, Licensee  shall
obtain, keep in force, and maintain Comprehensive or Commercial Form General
Liability Insurance (contractual liability included) or an equivalent program
of self-insurance with limits as follows:


                                       24
<PAGE>   46
        (a)  Each Occurrence [ *** ]
        (b)  Products/Completed Operations Aggregate [ *** ]
        (c)  Personal and Advertising Injury [ *** ]
        (d)  General Aggregate (commercial form only) [ *** ]

        It should be expressly understood, however, that the coverages and
limits referred to under the above shall not in any way limit the liability of
Licensee. Licensee shall furnish The Regents with certificates of insurance
evidencing compliance with all requirements. Such certificates shall:

                (18.2.1)        Provide a thirty (30)-day advance written
                                notice to the University of any modification.

                (18.2.2)        Indicate that The Regents has been endorsed as
                                an additional insured under the coverages 
                                referred to under the above.

                (18.2.3)        Include a provision that the coverages will be
                                primary and will not participate with nor will
                                be excess over any valid and collectible
                                insurance or program of self-insurance carried
                                or maintained by The Regents.

        18.3    The Regents shall promptly notify Licensee in writing of
any claim or suit brought against The Regents in respect of which The Regents
intends to invoke the provisions of this Article 18. Licensee will keep The
Regents informed on a current basis of its defense of any claims pursuant to
this Article 18.

                                  19.  NOTICES

        19.1    Any notice or payment required to be given to either party
shall be deemed to have been properly given and to be effective (a) on the date
of delivery if delivered in person or (b) five (5) days after mailing if mailed
by first-class certified mail, postage paid, to the respective 

*** confidential treatment is requested


                                       25
        
<PAGE>   47
addresses given below or to such other address as it shall designate by written
notice given to the other party.

In the case of the Licensee:    TISSUE TECHNOLOGIES INC.
                                1372 Green Street
                                San Francisco, CA 94109
                                Attention: Jesse Kramer

In the case of The Regents:     THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
                                1320 Harbor Bay Parkway, Suite 150
                                Alameda, California 94502
                                Attention: Director, Office of Technology 
                                  Transfer
                                Referring to: UC Case No. 93-057-1


                               20.  ASSIGNABILITY

        20.1    This Agreement is binding upon and shall inure to the benefit
of The Regents, its successors, and assigns, but shall be personal to the
Licensee and assignable to the Licensee only with the written consent of The 
Regents, which consent shall not be reasonably withheld.

                               21.  LATE PAYMENTS

        21.1    In the event royalty payments or fees or patent cost
reimbursements are not received by The Regents when due, the Licensee shall pay
to The Regents interest charges at a rate of [ *** ] per annum. Such interest
shall be calculated from the date payment was due until actually received by 
The Regents.

*** confidential treatment requested



                                       26
<PAGE>   48
                                  22.  WAIVER

        22.1    It is agreed that no waiver by either party hereto of any
breach or default of any of the covenants or agreements herein set forth shall
be deemed a waiver as to any subsequent and/or similar breach or default.

                            23.  FAILURE TO PERFORM

        23.1    In the event of a failure of performance due under the terms of
this Agreement and if it becomes necessary for either party to undertake legal
action against the other on account thereof, then the prevailing party shall be
entitled to reasonable attorney's fees in addition to costs and necessary 
disbursements.

                              24.  GOVERNING LAWS

        24.1    THIS AGREEMENT SHALL BE INTERPRETED AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF THE STATE OF CALIFORNIA, but the scope and validity of any
patent or patent application shall be governed by the applicable laws of the
country of such patent or patent application.

                25.  FOREIGN GOVERNMENT APPROVAL OR REGISTRATION

        25.1  If this Agreement or any associated transaction is required by the
law of any nation to be either approved or registered with any governmental
agency, the Licensee shall assume all legal obligations to do so.


                                       27
<PAGE>   49
                            26.  EXPORT CONTROL LAWS

        26.1    The Licensee shall observe all applicable United States and
foreign laws with respect to the transfer of Licensed Products and related
technical data to foreign countries, including without limitation, the
International Traffic in Arms Regulations (ITAR) and the Export Administration
Regulations.

                               27.  FORCE MAJEURE

        27.1    The parties to this Agreement shall be excused from any
performance required hereunder if such performance is rendered impossible or
unfeasible due to any catastrophes or other major events beyond their
reasonable control, including without limitation, war, riot, and insurrection;
laws, proclamations, edicts, ordinances, or regulations; strikes, lock-outs, or
other serious labor disputes; and floods, fires, explosions, or other natural
disasters. When such events have abated, the parties' respective obligations
hereunder shall resume.

                         28.  CONFIDENTIAL INFORMATION

        28.1    With regard to confidential information ("Data"), which can be
oral or written or both, and can include, but not be limited to, technical
information, patent applications, and prosecution documents received from The
Regents regarding this Invention, the Licensee agrees not to use the Data
except for the sole purpose of performing under the terms of this Agreement; to
safeguard Data against disclosure to others with the same degree of care as it
exercises with its own data of a similar nature; and not to disclose Data to
others (except to its employees, agents, or consultants who are bound to
Licensee by a like obligation of confidentiality) without the express 


                                       28
<PAGE>   50
written permission of The Regents except that Licensee shall not be prevented
from using or disclosing any of the Data:

        (28.1.1)        which Licensee can demonstrate by written records was
                        previously known to it;

        (28.1.2)        which is now, or becomes in the future, public
                        knowledge other than through acts or omissions of
                        Licensee; or

        (28.1.3)        which is lawfully obtained by Licensee from sources
                        independent of The Regents.

The secrecy obligations of Licensee with respect to Data shall continue for a
period ending five (5) years from the termination of this Agreement.

                               29. MISCELLANEOUS

        29.1 The headings of the several sections are inserted for convenience
of reference only and are not intended to be part of or to affect the meaning
or interpretation of this Agreement.

        29.2 This Agreement will not be binding upon the parties until it has
been signed below on behalf of each party; in which event, it shall be
effective as of the date recited on page one.

        29.3 No amendment or modification hereof shall be valid or binding upon
the parties unless made in writing and signed on behalf of each party.

        29.4 This Agreement embodies the entire understanding of the parties
and shall supersede all previous communications, representations, or
understandings, either oral or written,

                                       29
<PAGE>   51
between the parties relating to the subject matter hereof. The Letter of Intent
effective June 14, 1993, UC Control No. 93-30-0385 is hereby terminated.

        29.5 In case any of the provisions contained in this Agreement shall be
held to be invalid, illegal, or unenforceable in any respect, such invalidity,
illegality, or unenforceability shall not affect any other provision hereof,
but this Agreement shall be construed as if such invalid or illegal or
unenforceable provisions had never been contained herein.

        IN WITNESS WHEREOF, both The Regents and the Licensee have executed
this Agreement in duplicate originals by their respective officers hereunto
duly authorized, on the day and year hereinafter written.

TISSUE TECHNOLOGIES INC.:               THE REGENTS OF THE
                                        UNIVERSITY OF CALIFORNIA:

By: /s/ Jesse Kramer                    By: /s/ William T. Davis
    -------------------------               --------------------------------

Name: Jesse Kramer                      Name: William T. Davis
      -----------------------                 ------------------------------

Title: President                              Associate Director 
       ----------------------                 Office of Technology Transfer

Date: 3/21/94                           Date: 3/31/94   
      -----------------------                 ------------------------------

                                       30