EXHIBIT 10.5

                                   DEVELOPMENT AND
                             COMMERCIALIZATION AGREEMENT
                                           
    THIS DEVELOPMENT AND COMMERCIALIZATION AGREEMENT (together with the
attached Schedule, the "Agreement") is dated as of September 25, 1997 (the
"Effective Date") by and between Genzyme Transgenics Corporation, a
Massachusetts corporation with a business address at Five Mountain Road,
Framingham, Massachusetts 01701-9322 ("GTC") and Advanced Cell Technology, Inc.,
a Delaware corporation with a business address at One Innovation Drive,
Worcester, Massachusetts 01605 ("ACT").

1.  Background. 
    
    1.1. GTC.  GTC is a biopharmaceutical company with experience in the 
         production of recombinant human proteins/products in the milk of 
         animals through the application of transgenic technology. GTC has 
         developed proprietary technologies suitable for the transgenic 
         production of recombinant human serum albumin ("hSA"), and has a 
         program to produce hSA in the milk of transgenic cattle. 

    1.2. ACT.  ACT is engaged in, among other fields, the research and
         development of [*] and the cloning of transgenic cattle derived
         therefrom.

    1.3. hSA Project.   GTC and ACT are interested in the development  of
         Transgenic Cattle (defined below)  generated through application of
         the ACT Technology (defined below) which produce hSA, in their milk,
         and the commercialization of such transgenically produced hSA.

    1.4. Other Projects.   GTC and ACT also are interested in the development 
         of Transgenic Cattle generated through application of the ACT
         Technology which produce other recombinant proteins/products in their
         milk, and the commercialization of such transgenically produced
         proteins/products.

    1.5. Exclusive Relationship with GTC.  Subject to the terms and conditions
         of this Agreement, ACT shall work exclusively with GTC in the Field
         (defined below).

2.  Definitions.  As used in this Agreement, the following terms shall have the
    meanings set forth below.

    2.1. "Affiliate" means any corporation, company, partnership, joint venture
         and/or firm which controls, is controlled by or is under common
         control with a Party.  For purposes of this Section 2.2, "control"
         means (a) in the case of corporate entities, direct or indirect
         ownership of more than fifty percent (50%) of the stock or shares
         entitled to vote for the election of directors; and (b) in the case of
         non-corporate entities, direct or indirect ownership of more than 
         fifty

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         percent (50%) of the equity interest with the power to direct
         the management and policies of such noncorporate entities. 
         Notwithstanding the foregoing, Genzyme Corporation shall be deemed an
         Affiliate of GTC for purposes of this Agreement.

    2.2. "ACT Patent Rights" means any and all patents and patent applications
         owned or licensed by ACT in which ACT has a licensable interest and
         which exists as of the date of this Agreement or which come into
         existence during the term of this Agreement which are useful,
         necessary or required for the Parties to perform their respective
         obligations under this Agreement.  ACT Patent Rights shall include any
         reissues, extensions (or other governmental acts which effectively
         extend the period of exclusivity by the patent holder), substitutions,
         confirmations, registrations, revalidations, additions, continuations,
         continuations-in-part, divisions or foreign counterparts of or to the
         foregoing patent rights.  ACT Patent Rights include, without
         limitation, the patents and patent applications listed on Schedule A
         attached to this Agreement.

    2.3. "ACT Technology" means the following which are owned or controlled by
         ACT during the term of this Agreement which are useful, necessary or
         required for the Parties to perform their respective obligations under
         this Agreement: confidential information, knowledge and data,
         including but not limited to, inventions (whether patentable or not),
         trade secrets, ideas, designs, drawings, know-how, processes,
         techniques and like technological information pertaining to the
         derivation, maintenance and use of [*] for the generation of
         transgenic or other cattle.  Additionally, ACT Technology shall
         include any process described within the ACT Patent Rights.

    2.4. "BLA" means a United States biologics license application or its
         foreign counterparts.
    
    2.5. "Confidential Information" includes, without limitation, any
         scientific, technical, trade or business information disclosed by one
         party to the other which is treated or otherwise identified by the
         party providing such information as confidential or proprietary.

         "Confidential Information" does not include information which (a) was
         known to the receiving Party at the time it was disclosed, other than
         by previous disclosure by the disclosing Party, as evidenced by
         written records at the time of disclosure; (b) is at the time of
         disclosure or later becomes publicly known under circumstances
         involving no breach of this Agreement; (c) is lawfully and in good
         faith made available to the receiving Party by a third party who did
         not derive it from the disclosing Party and who imposes no obligation
         of confidence on the receiving Party; or (d) is developed by the
         receiving Party independent of any disclosure by the disclosing Party.

    2.6. "Developments" include, without limitation, discoveries, inventions,


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         developments, patents and patent rights, know-how, trade secrets,
         techniques, methodologies, modifications, innovations, improvements,
         writings, documentation, data and rights (whether or not protectible
         under state, federal, or foreign patent, trademark, copyright or
         similar laws) that are conceived, discovered, invented, developed,
         created, made or reduced to practice by or on behalf of one or both of
         the Parties in performing their respective obligations under this
         Agreement.

    2.7. "FDA" means the United States Food and Drug Administration.

    2.8. "Field" means the manufacture, use, import, sale or other
         commercialization of (a) recombinant human proteins/products which are
         produced in the milk of Transgenic Cattle for pharmaceutical,
         Nutraceutical and/or other therapeutic uses, (b) other recombinant
         proteins/products which are produced in the milk of Transgenic Cattle
         for such  uses in humans, and (c) the Transgenic Cattle which produce
         such proteins/products.  The Field does not include the development of
         Transgenic Cattle for any other purposes, including, without
         limitation, the development of cattle with improved agricultural
         and/or veterinary characteristics (e.g., milk yields, animal size or
         disease resistance).

    2.9. "GTC Technology" means the following which are owned or controlled by
         GTC: confidential information, knowledge and data, including but not
         limited to, inventions (whether patentable or not), trade secrets,
         ideas, designs, drawings, know-how, processes, techniques and like
         technological information pertaining to the transgenic production of
         recombinant proteins/products in the milk of transgenic animals, which
         are useful, necessary or required for the Parties to perform their
         respective obligations under this Agreement.

   2.10. hSA Project" means the production, through application of the
         ACT Technology, of Transgenic Cattle which contain the hSA
         transgene and express hSA in their milk, as set forth on the hSA
         Project Summary attached to this Agreement as Schedule B.

   2.11. Net Sales" means the aggregate United States dollar equivalent
         of gross revenues derived by or paid to GTC (or its Affiliates,
         if applicable) from or on account of the sales or transfers of
         the Transgenic Cattle developed by ACT under this Agreement, or
         the proteins/products produced in the milk of such Transgenic
         Cattle, to third parties which are not Affiliates, less
         (a) reasonable credits or allowances, if any, actually granted on
         account of price adjustments, recalls, rejection or return of
         items previously sold, (b) excises, sales taxes, value added
         taxes, consumption taxes, duties or other taxes imposed upon and
         paid with respect to such sales (excluding income or franchise
         taxes of any kind) and (c) separately itemized insurance and
         transportation costs incurred in shipping such proteins/products
         to such third parties.  No deduction shall be 

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         made for any item of cost incurred by GTC in preparing, manufacturing,
         shipping or selling such proteins/products except as permitted 
         pursuant to clauses (a), (b) and (c) of the foregoing sentence.

         In addition, in order to ensure the full royalty payments contemplated
         under this Agreement, in the event any Transgenic Cattle or the
         proteins/products produced in the milk of such Transgenic Cattle are
         sold to any Affiliate or corporation, firm or association with which
         GTC has an agreement, understanding or other arrangement with respect
         to other  forms of consideration (for example, an option to purchase
         stock or actual stock ownership; an arrangement involving division of
         profits or special rebates or allowances) royalties shall be
         calculated for sales of such Transgenic Cattle/proteins/products 
         based upon the fair market value of such Transgenic
         Cattle/proteins/products, as determined by the Liaison Committee.

         Notwithstanding the foregoing, no transfer of such proteins/products
         for testing, pre- clinical, clinical or developmental purposes or as
         samples shall be considered a sale hereunder for accounting and
         royalty purposes.

   2.12. "Nutraceutical" means any food or other preparation intended for
         consumption by humans which, when taken into the human body, (a)
         serves to nourish or build up tissues or supply energy and/or (b)
         maintains, restores or supports adequate nutritional status or
         metabolic function.

   2.13. "Party" means GTC or ACT; "Parties" means GTC and ACT.

   2.14. "Transgenic Cattle" means cattle (including, without limitation,
         transgenic eggs, semen and embryos and progeny thereof) that are
         produced under this Agreement (a) with or by use of the ACT
         Technology, (b) are transfected with GTC's recombinant DNA
         constructs and (c) are used for the sole purpose of transgenic
         production of recombinant proteins/products in milk. 

3.  Liaison Committee.   Within thirty (30) days of the Effective Date, GTC and
    ACT shall form a committee (the "Liaison Committee") to coordinate the
    Parties' activities under this Agreement.  The Liaison Committee shall
    consist of four (4) members, two (2) of whom shall be designated by GTC and
    two (2) of whom shall be designated by ACT.  Each Party may assign its
    members to the Liaison Committee as it deems appropriate, and designated
    substitutes may represent Liaison Committee members at regularly scheduled
    meetings at the discretion of the substituting Party.  The Liaison
    Committee will meet at least once per calendar quarter, alternating between
    GTC and ACT locations, to assess the progress under this Agreement.  In
    addition to reports to, and meetings of, the Liaison Committee, there will
    be frequent communications among the scientists and project managers to
    keep ACT and GTC advised of current activities of the Parties under this
    Agreement.


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4.  hSA Project.

    4.1. hSA Project Summary.  Immediately upon execution of this Agreement,
         the Parties will initiate the hSA Project pursuant to the hSA Project
         Summary attached to this Agreement as Schedule B.  The hSA Project
         Summary may  be modified only  by  agreement of the Parties. 

    4.2. Responsibilities of ACT for hSA Project.

         a.   Conduct of the hSA Project.  ACT shall provide qualified
              technical and managerial staff to conduct the hSA Project.  ACT
              shall provide a team of at least two individuals (the "ACT's hSA
              Project Team") to supply expertise in the areas of [*].

         b.   Provision of Facilities.  ACT shall provide all facilities and
              equipment acceptable to GTC which are necessary for the conduct
              of the hSA Project, including space, housing and utilities
              services necessary to maintain [*].  All bovine stock for the hSA
              Project will be housed at a facility controlled by ACT or, with
              GTC's prior written consent, an ACT designated facility under the
              control of a third party.

         c.   Sources of Cattle.  ACT shall provide heifers selected in
              accordance with good agricultural practice ("GAP") criteria
              provided by GTC and agreed upon by ACT, as are necessary to
              conduct the hSA Project.  All Transgenic Cattle used and/or
              produced by ACT under this Agreement shall be free from bovine
              spongiform encephalopathy and/or other infectious agents.  If, at
              any time during the term of this Agreement, ACT and/or GTC have
              any reason to believe (or have any reason to conclude that a
              governmental regulatory authority believes) that bovine
              spongiform encephalopathy and/or other infectious agents have or
              may be detected in cattle in the United States, ACT will promptly
              institute procedures acceptable to the Parties to ensure the
              health of the Transgenic Cattle used and/or produced by ACT under
              this Agreement.

         d.   [*]

         e.   Care of Animals.  ACT or its designee shall have sole
              responsibility for the care and maintenance of all bovine stock
              used and generated during the hSA Project, as defined in the hSA
              Project Summary.  ACT shall also provide all required feed and
              veterinary care.

         f.   Animal Welfare Regulations.  The hSA Project shall undergo
              then-applicable animal welfare and animal research committee
              review and approval by GTC and ACT in accordance with
              then-applicable standards.



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         g.   Compliance with Other Regulations.  ACT shall conduct all aspects
              of the hSA Project in full compliance with USDA, FDA and other
              regulatory requirements for the production of clinical-grade
              proteins/products in the milk of transgenic animals; provided,
              however, in the event that regulatory requirements significantly
              and materially change during the term of this Agreement for the
              hSA project or other projects under Section 5, below, such that
              ACT's compliance therewith would result in significantly
              increased costs for ACT, then such change in regulatory
              requirements shall be deemed an event of force majeure under this
              Agreement; and further provided, that in the event of force
              majeure under this Section, GTC, at its option, may elect the
              remedies set forth in Section 7.10 of this Agreement for any
              project for which ACT has declared an event of force majeure. 
              GTC shall have the ongoing right to audit ACT's compliance with
              this Section and other Sections of the Agreement to ensure such
              compliance.

    4.3. Responsibilities of GTC for hSA Project.

         a.   GTC's hSA Project Team.  GTC shall provide a team of two
              individuals ("GTC's hSA Project Team") to supply expertise in
              transgenic expression of hSA in the milk of cattle.  GTC's hSA
              Project Team shall consult with ACT's hSA Project Team in the
              transfection of hSA constructs into [*].

         b.   DNA Constructs. GTC's hSA Project Team shall assist ACT's hSA
              Project Team by providing all necessary DNA constructs jointly
              deemed necessary by the Parties for use in the hSA Project,
              including, without limitation, the [*] and/or other suitable
              selectable markers.

         c.   Identification of Transgenic Lines and Animals.  GTC shall
              provide all materials and resources necessary for the
              identification and evaluation of [*].  Such materials shall
              include, without limitation, DNA probes and polymerase chain
              reaction ("PCR") primers.

         d.   Other Expertise.  GTC's hSA Project Team shall provide additional
              expertise, as reasonably necessary, during the course of the hSA
              Project, including, without limitation, lactation induction, and
              pharmaceutical protein purification, characterization and
              regulatory advice.

         e.   Characterization of Transgenic Cattle.  Following the birth of
              Transgenic Cattle generated during the hSA Project, GTC shall




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              characterize individual animals derived from specific recombinant
              cell lines, and elect whether to expand the Transgenic Cattle
              from select cell lines.  Characterization shall be comprised of
              genotyping, animal health and measurement of the levels of hSA in
              the induced and/or natural lactation of such Transgenic Cattle.
 
    4.4. hSA Project Compensation.  GTC shall pay ACT the following
         compensation in consideration of ACT's work under the hSA Project:

         a.   Base Fee. GTC shall pay ACT a [*] within [*].

         b.   [*].  GTC shall pay ACT a [*] payable in up to [*] with each
              payment due within [*].

         c.   Success Fee.  GTC shall pay ACT a [*] upon achievement by ACT of
              [*].  The success fee shall be paid within [*].

         d.   [*].

         e.   [*].
         
    4.5. hSA Commercialization.  Following characterization of the Transgenic
         Cattle generated during the hSA Project, GTC may elect from the
         following options:

         a.   ACT to Expand Herd and Produce hSA-Containing Milk.  Subject to
              ACT's consent, GTC may contract with ACT for the expansion of the
              Transgenic Cattle herd and the production of hSA in the milk of
              the Transgenic Cattle generated through the use of the ACT
              Technology.  In such event, the Parties shall enter a separate
              supply agreement, which shall include among its terms, without
              limitation, the following provisions:

              a.   Non-Commercial Supply.  ACT shall supply GTC exclusively
                   with hSA-containing milk from Transgenic Cattle, at
                   competitive prices  to be agreed upon by the Parties, for
                   use solely by GTC, its Affiliates and corporate partners in
                   processing and testing, and for the conduct of clinical
                   trials (i.e., for non-commercial purposes).  The form of
                   such milk and the specifications thereof will be determined
                   by the Liaison Committee.

              b.   Herd Expansion Costs.  GTC shall pay or reimburse ACT, at
                   commercially reasonable and competitive prices to be agreed
                   upon by the Parties, for the herd expansion necessary for
                   ACT to supply GTC with hSA-containing milk for




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                   non-commercial and commercial purposes, and for any other
                   scale-up expenses authorized by the Liaison Committee.

              c.   Commercial Supply.  ACT shall use commercially reasonable
                   and diligent efforts (or shall cause a third party
                   acceptable to GTC to use commercially reasonable and
                   diligent efforts) to (a) develop a number of Transgenic
                   Cattle expected to produce sufficient quantities of hSA to
                   meet GTC's (and its Affiliates' and corporate partners')
                   commercial and regulatory  requirements for hSA and (b)
                   supply GTC and its Affiliates and corporate partners with
                   the quantities of hSA-containing milk for such commercial
                   purposes, at a commercially reasonable price per gram to be
                   separately agreed to by the Parties.  Unless otherwise agree
                   to by the Parties, GTC, at its cost and expense, will
                   process the hSA-containing milk supplied by ACT and
                   formulate the hSA contained therein.  GTC shall conduct all
                   necessary testing and other studies, and shall make all
                   regulatory filings, necessary to market and sell
                   transgenically-produced hSA.  ACT shall provide GTC with
                   data which relates to hSA produced under this Agreement and
                   ACT's performance of its obligations under this Agreement
                   which is reasonably necessary to support such regulatory
                   filings.

                   In the event GTC elects to have ACT supply it with
                   hSA-containing milk for commercial purposes, the Liaison
                   Committee shall agree upon terms regarding (i) the form of
                   the hSA to be supplied (e.g., hSA-containing whole milk,
                   freeze-dried milk, condensed milk or spray-dried milk); (ii)
                   the specifications for such hSA and milk and the resulting
                   price to be paid therefor; (iii) QA/release testing
                   requirements; (iv) the certificate of analysis; (v) GTC's
                   acceptance testing; (vi) quarterly twelve-month rolling
                   forecast procedures; (vii) order and delivery times; and
                   (viii) other usual and customary terms. 

         b.   GTC to Take Possession of Transgenic Cattle.  As set forth in
              Section 7.1, below, all Transgenic Cattle produced by ACT under
              this Agreement are owned by GTC, and GTC may take possession of
              some or all of the Transgenic Cattle produced by ACT and may
              maintain (or have a third party maintain, with ACT's reasonable
              assistance, as necessary, with such assistance to be paid for by
              GTC based upon agreements between the Parties, following the
              procedures set forth in Section 4.4(d) hereof) such Transgenic
              Cattle at any location; provided, however, (i) GTC shall give ACT
              the first opportunity (either directly or with a collaborator
              acceptable to GTC) to expand the herd and produce hSA in the milk


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              of Transgenic Cattle, and to supply such milk to GTC, as provided
              in Section 4.5(a), above, and (ii) to the extent GTC takes
              possession of such Transgenic Cattle, (A) GTC shall only  use
              such Transgenic Cattle for the production of hSA from milk and
              (B) GTC may expand such Transgenic Cattle herd using breeding or
              other techniques which do not use the ACT Patent Rights.  For
              avoidance of doubt, however, the sale of hSA produced in the milk
              of such Transgenic Cattle shall be subject to  royalty payments
              to ACT, as set forth in Section 7.9, below.

         c.   Discontinue Herd Expansion.  GTC may discontinue further herd
              expansion from such Transgenic Cattle.

5.  Other Projects.

    5.1. Development and Commercialization.  In addition to the hSA Project,
         ACT shall collaborate with GTC on the production of (a) other
         recombinant proteins/products which are produced in the milk of
         Transgenic Cattle for pharmaceutical and/or Nutraceutical uses in the
         Field, and (b) the Transgenic Cattle which produce such recombinant
         proteins/products, on the basic terms set forth in this Agreement
         (including, without limitation, the terms for hSA set forth in Section
         4, above; provided, however, the Parties shall adjust the amount and
         timing of payments up or down taking into account the size, complexity
         and commercial nature of each project) and on such other reasonable
         and customary terms which may be negotiated by the Parties in good
         faith prior to the commencement of each separate project.  The
         corporate form of such collaborations shall be subject to GTC's
         requirements under contracts with third parties. In the course of such
         collaboration, GTC will not require ACT to make significant capital
         investments or similar long-term expenditure commitments, unless GTC
         has first (i) discussed with ACT the need for capital investment and
         other expenditures; (ii) identified appropriate schedules and plans
         for the use of such capital investments and other expenditures; and
         (iii) provided ACT with reasonable business commitments for the use of
         such investments and other expenditures in collaborative projects
         under this Agreement.

    5.2. ACT Exclusivity in Field; Project Scope.

         a.   Exclusivity.  During the term of this Agreement, ACT shall work
              exclusively with GTC in the Field, subject to the conversion
              provision set forth in Section 5.3, below.

         b.   Scope.  GTC shall use commercially reasonable efforts to
              collaborate with ACT on commercially available projects which


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              generate the maximum achievable payments to ACT per project per
              year, such that ACT shall have an opportunity to work efficiently 
              by conducting a limited number of  significant projects in return
              for the annual payments set forth below.  

    5.3. Minimum Annual Payments.

         a.   Minimum Annual Payments for Initial Two Year Period; Limited
              Right to Cease Such Payments.  GTC agrees that it shall make
              minimum annual payments of not less than Two Million Dollars
              ($2,000,000) per year to ACT for calendar years 1998 and 1999
              (the "Initial Two Year Period"), except as follows:  If, by
              reason of force majeure, scientific/technical difficulties or
              legal proceedings or the threat of legal proceedings (for
              example, without limitation, a patent infringement action brought
              by a third party), ACT is unable to perform its obligations under
              this Agreement, and such inability continues for a period of six
              (6) months, GTC shall not be required to continue such minimum
              annual payments to ACT, and ACT shall have the right at any time
              thereafter, in its sole discretion and upon sixty (60) days prior
              written notice to GTC, to convert the exclusive arrangement in
              the Field to non-exclusive only with respect to any future
              proteins/products from Transgenic Cattle developed by ACT for GTC
              under this Agreement; provided, however, GTC may, at its option,
              preserve the exclusivity of its arrangement with ACT in the Field
              for such future proteins/products if, within said 60 day period,
              it pays to ACT the balance of the minimum annual payments due for
              such calendar year.   ACT's arrangement with GTC shall remain
              exclusive for any proteins/products for which GTC has paid ACT
              development or other payments in a significant funded project
              under this Agreement.

         b.   Minimum Annual Payments for Subsequent Three Year Period; Limited
              Right to Cease Such Payments.  GTC agrees that it shall make
              minimum annual payments of not less than Two Million Dollars
              ($2,000,000) per year to ACT for calendar years 2000, 2001 and
              2002 (the "Subsequent Three Year Period"), except as follows:  If
              (i) by reason of force majeure, scientific/technical difficulties
              or legal proceedings or the threat of legal proceedings (for
              example, without limitation, a patent infringement action brought
              by a third party), ACT is unable to perform its obligations under
              this Agreement, or (ii) ACT has not achieved milestones (to be
              set forth on Schedule B on a protein-by protein basis),
              including, but not limited to, technical success defined to
              include natural lactation of Transgenic Cattle for any one of the
              then-existing projects contracted to ACT under this Agreement
              beginning in calendar year 2000, then GTC shall not be required


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              to continue such minimum annual payments to ACT, and ACT shall
              have the right at any time thereafter, in its sole discretion and
              upon sixty (60) days prior written notice to GTC, to convert the
              exclusive arrangement in the Field to non-exclusive only with
              respect to any future proteins/products from Transgenic Cattle
              developed by ACT for GTC under this Agreement; provided, however,
              GTC may, at its option, preserve the exclusivity of its
              arrangement with ACT in the Field for such future
              proteins/products if, within said 60 day period, it pays to ACT
              the balance of the minimum annual payments due for such calendar
              year.  ACT's arrangement with GTC shall remain exclusive for any
              proteins/products for which GTC has paid ACT development or other
              payments in a significant funded project under this Agreement.

         c.   Following Subsequent Three Year Period.  Beginning in calendar
              year 2003, GTC shall have the option to continue the exclusive
              arrangement in the Field by making minimum annual payments of not
              less than [*] per year to ACT.  In the event GTC elects for any
              reason not to make such minimum annual payments, it shall provide
              ACT with written notice of such election on or before October 1st
              in the year prior to the year in which such minimum annual
              payments would otherwise be due.  If ACT has not received such
              written notice from GTC on or before October 1st in a given
              calendar year, ACT shall contact GTC within ten (10) business
              days of October 1st regarding GTC's intention or lack of
              intention to make minimum annual payments for the following
              calendar year.  Within ten (10) additional business days of
              receipt of this inquiry from ACT, GTC shall confirm in writing
              its intentions with respect to such annual minimum payments.  If,
              following the above-stated procedure, GTC has affirmatively
              elected not to make such minimum annual payments for the next
              calendar year, then ACT shall have the right, at any time in its
              sole discretion and upon sixty (60) days prior written notice to
              GTC, to convert the exclusive arrangement in the Field to
              non-exclusive only with respect to any future proteins/products
              from Transgenic Cattle developed by ACT for GTC under this
              Agreement.  ACT's arrangement with GTC shall remain exclusive for
              any proteins/products for which GTC has paid ACT development or
              other payments in a significant funded project under this
              Agreement.

         d.   Credits.  Unless otherwise adjusted by the Liaison Committee to
              fairly balance the Parties' interests, up to [*] in minimum
              annual payments made by GTC under this Section 5.3 in any year
              solely to preserve exclusivity in the Field shall be creditable
              against work performed or to be performed by ACT, and against
              future annual obligations incurred by GTC, on or before October
              1st in the next calendar year. 


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         e.   Source of Minimum Annual Payments.  The source of the minimum
              annual payments set forth in this Section may include, without
              limitation, funds from the hSA Project (other than funds payable
              under Sections 4.4(a) and (b), above), new project fees, research
              and development payments (other than success fees paid under
              Section 5.4), royalties on product sales, or any other payments
              made to ACT by GTC which specifically and directly relate to its
              work under this Agreement.

         f.   Minimum Annual Payments Subject to Satisfaction of Technical
              Requirement.  GTC's obligation to make minimum annual payments to
              ACT under this Section 5.3 is subject to ACT satisfying the
              following requirement: ACT, on an ongoing basis, must  provide
              GTC with sufficient technical information regarding ACT's use and
              development of  the ACT Patent Rights and ACT Technology in the
              Field, such that the Parties can negotiate a separate Schedule B
              for each project brought to ACT by GTC under this Agreement.

    5.4. Success Fee.  GTC shall pay ACT a success fee upon achievement by ACT
         of an agreed-upon expression level for each protein produced by ACT or
         other appropriate success criteria agreed to by the Parties prior to
         commencement of the particular protein production project.  The
         success fee shall be not less than [*], and may be increased by
         agreement of the Parties.

6.  Option for Rights to Transgenic Goats and Rabbits; Equity Investment.  

    6.1. Option for Rights to Transgenic Goats and Rabbits. GTC shall have an
         option, exercisable by written notice to ACT during the first eighteen
         (18) months of this Agreement, to expand the scope of this Agreement,
         including, without limitation, the license set forth in Section 7.6,
         below, to cover the production, using the ACT Patent Rights and the
         ACT Technology, of recombinant proteins/products in the milk of cloned
         transgenic goats and rabbits for use in the Field, on reasonable and
         customary terms and conditions to be negotiated by the Parties.

    6.2. Equity Investment.  Subject to valuation and other terms to be agreed
         to by the Parties, including, without limitation, restrictions on
         ACT's rights to sell any such GTC stock, and customary registration
         and participation rights with respect to any private placement or
         public offering of securities by ACT, GTC shall acquire equity in ACT,
         valued at [*], for cash or GTC stock.  GTC shall make any such
         investment (a) within thirty (30) days of the date ACT notifies GTC,
         and the Liaison Committee confirms, the birth of the first of the
         Transgenic Cattle produced by ACT for GTC under this Agreement or (b)
         December 31, 1998, whichever is earlier.


                                      -12-

*Confidential Treatment has been requested for the marked portion.



7.  Proprietary Rights.

    7.1. GTC.  GTC shall own the GTC Technology, all proprietary DNA
         constructs, all recombinant cell lines generated with GTC's DNA
         constructs, and the Transgenic Cattle produced during the hSA Project
         and other projects under this Agreement.

    7.2. ACT.  ACT shall own the ACT Patent Rights and ACT Technology, together
         with any improvements thereto.

    7.3. Joint Developments. The Parties shall jointly own all Developments
         conceived, discovered, invented, developed, created, made or reduced
         to practice by both Parties in the Field in performance of their
         obligations under this Agreement.  Ownership of Developments shall be
         determined according to U.S. patent law.
 
    7.4. Filing and Maintenance of Patents on Joint Developments.  GTC shall
         have the right to decide whether or not to seek or continue to seek or
         maintain patent protection on jointly-developed Developments in any
         country in the world, and shall have the right, jointly in its and
         ACT's name, to file for, procure, and maintain patents on any such
         Developments in any country in the world, with the expenses being
         borne by GTC.  If GTC elects not to seek or continue to seek or
         maintain patent protection on any jointly- developed Developments in
         any country in the world, GTC promptly shall notify ACT thereof in
         writing, and ACT shall have the right, in its name, to file, procure
         and maintain in such countries patents on such jointly-developed
         Developments, with the expenses being borne by ACT.  GTC agrees to
         advise ACT in writing of all decisions taken under this Subsection in
         a timely manner, but in any case at least ninety (90) days prior to
         the time any action is required, in order to allow ACT to decide to
         take any such action, and to take such action, related to the
         jointly-developed Developments.

    7.5. Patent Cooperation.  Each Party shall provide the other Party with
         copies of all substantive communications from all patent offices
         regarding applications or patents on any jointly-developed
         Developments promptly after the receipt thereof.  Each Party shall
         provide the other Party with copies of all proposed substantive
         communications to such patent offices regarding applications or
         patents on any such jointly-developed Developments in sufficient time
         before the due date in order to enable the other Party an opportunity
         to comment on the content thereof.  Each Party shall make available to
         the other Party or its authorized attorneys, agents, or
         representatives, such of its employees whom the other Party in its
         reasonable judgment deems necessary in order to assist it in pursuing
         patent protection for the jointly-developed Developments.  Each Party
         shall sign or use its best efforts to have signed (at no cost to the
         other Party) all legal documents necessary to file and prosecute
         patent applications or to obtain or maintain patents on any
         jointly-developed Developments.


                                      -13-



    7.6. License.  In order to enable GTC to perform its obligations under, and
         realize the benefits of, this Agreement, ACT grants to GTC and its
         Affiliates:

         a.   an exclusive, worldwide, royalty-bearing license under the ACT
              Patent Rights; and

         b.   an exclusive, worldwide, royalty-bearing license to use the ACT
              Technology,

         including the right to grant sublicenses, limited to the Field, for
         the sole and exclusive purposes of (i) using, importing, selling and
         have sold, the Transgenic Cattle produced by ACT under this Agreement
         and (ii) making, having made, using, importing, selling and have sold,
         the proteins/products produced in such Transgenic Cattle, on the basic
         terms set forth in this Agreement and on such other reasonable and
         customary terms which may be negotiated by the parties in good faith.
  
         The licenses granted pursuant to Section 7.6.a  shall continue in
         effect until the expiration of the last patent licensed to GTC
         hereunder.  The licenses granted pursuant to Section 7.6.b. shall
         continue in effect for twelve (12) years from the date of first
         commercial sale of product developed by or on behalf of ACT under this
         Agreement;  provided, however, GTC shall have a renewable right to
         extend such licenses for successive twelve (12) year terms by delivery
         of written notice to ACT.

    7.7. Conversion to Non-Exclusive Licenses.  In the event that GTC fails to
         meet the minimum annual payment requirements set forth in Section 5.3,
         above, ACT shall have the right at any time thereafter, upon sixty
         (60) days prior written notice to GTC, to convert the license set
         forth in Section 7.6, above, from exclusive to non-exclusive with
         respect to any proteins/products from Transgenic Cattle which, as of
         such date, are not being developed by ACT for GTC in a significant
         funded project under this Agreement; provided, however, GTC may, at
         its option, preserve the exclusivity of such license if, within said
         60 day period, it pays to ACT the balance of the annual minimum
         purchase requirement then due for such calendar year; and further
         provided, that GTC's license shall remain exclusive with respect to
         all proteins/products from Transgenic Cattle previously developed by
         ACT for GTC in a significant funded project under this Agreement.

    7.8. Commercialization Fee.  For each transgenic protein produced in
         Transgenic Cattle developed  by ACT under this Agreement, GTC shall
         pay to ACT a commercialization fee equivalent to [*] of GTC's


                                      -14-



         estimated sales of each such protein during the fifth (5th) year
         following commercial launch of such protein, with such
         commercialization fee not to exceed [*] for any one transgenic
         protein.  Such estimate shall be made by GTC in good faith using its
         best sales projections, and shall be payable to ACT within ninety (90)
         days of the date GTC's BLA for each such protein is approved by the
         FDA.

    7.9. Royalties.  GTC shall pay to ACT the following royalties:

         a.   Milk from Transgenic Cattle Developed by ACT.  GTC shall pay ACT
              the following applicable percentage of Net Sales during the term
              of the licenses granted to GTC under Section 7.6, above:

              [*]

         b.   Milk from Transgenic Cattle Developed by Third Parties.  In the
              event ACT undertakes a development project for GTC under this
              Agreement to produce a particular protein in the milk of
              Transgenic Cattle, and GTC does not use the resulting Transgenic
              Cattle to produce such protein, but instead produces such protein
              in cattle developed by GTC outside of this Agreement, then GTC
              shall pay to ACT a [*] royalty on Net Sales of proteins/products
              from milk produced in such cattle.

         c.   Royalty Rate upon Conversion to Non-Exclusive.  In the event
              ACT's exclusive arrangement with GTC in the Field converts to
              nonexclusive, as set forth in Section 7.7, above, the royalty
              payable to ACT on Net Sales of proteins/products from Transgenic
              Cattle developed by ACT in projects which commenced following
              such conversion to nonexclusive shall be fifty percent (50%) of
              the royalty rates set forth above.

         d.   Audits.  ACT and/or its qualified designated representative shall
              have the right to audit, in confidence, those books and records
              of GTC which relate to amounts payable to ACT under this Section
              7.9.  Such audits shall require reasonable prior notice to GTC
              and may not occur more than once per calendar year. 

   7.10. Failure or Inability to Perform.   

         a.   Causes of Nonperformance.  If, for any reason, and at any time
              any of the following events occur, the Parties immediately shall
              meet to determine and agree upon what actions ACT will take, to
              GTC's reasonable satisfaction, in response to the such
              occurrence:


                                      -15-


*Confidential Treatment has been requested for the marked portion.




              i.   if ACT is unable to develop and produce cloned Transgenic
                   Cattle for GTC under this Agreement, and such inability
                   lasts for more than one hundred twenty (120) days longer
                   than the agreed-upon date of delivery of such Transgenic
                   Cattle;

              ii.  Subject to Section 5.1, ACT is unable or unwilling to make
                   the investments in the physical and human resources deemed
                   reasonably necessary by the Liaison Committee for ACT to
                   perform its obligations under this Agreement;

              iii. failure by ACT to institute appropriate procedures against
                   bovine spongiform encephalopathy and/or other similar
                   infectious agents, as set forth in Section 4.2(c), above; or

              iv.  any person or entity not previously an ACT Affiliate
                   acquires all or a controlling interest in the equity of ACT
                   or any of its Affiliates, or of all or substantially all of
                   the assets of ACT, without the agreement of such party to be
                   bound by this Agreement.

         b.   Performance Failure.  If ACT fails to take appropriate action, to
              GTC's reasonable satisfaction, in response to the occurrence of
              any of the events listed in Section 7.10(a), above, within sixty
              (60) days of the occurrence of such event, or if at any time ACT
              ceases its operations, GTC may declare that a "Performance
              Failure" has occurred.  GTC shall notify ACT promptly in writing
              upon the declaration or occurrence of any Performance Failure. 
              In the event of a Performance Failure, GTC may, at its sole
              option and without prejudice to any other remedy it may have,
              terminate this Agreement under Section 10, below, and thereafter
              manufacture itself or have manufactured all or any part of its
              requirements for Transgenic Cattle, and/or the proteins/products
              produced in such Transgenic Cattle, utilizing the ACT Patent
              Rights and ACT Technology.  ACT, at GTC's cost and expense, shall
              immediately transfer to GTC the exclusive right to use the ACT
              Patent Rights and ACT Technology in the Field.  In addition, ACT,
              at GTC's own cost and expense, will promptly and diligently
              provide GTC with the all reasonable technical assistance, so that
              GTC may use the ACT Patent Rights and ACT Technology to develop,
              use, conduct preclinical and clinical studies for, register for
              governmental medical or pricing approval, manufacture, have
              manufactured, distribute and/or sell the proteins/products
              produced in the milk of cloned Transgenic Cattle.   In the event
              GTC elects to manufacture or have a third party manufacture
              cloned Transgenic Cattle and/or the proteins/products produced in
              such clone Transgenic Cattle, GTC shall pay ACT a fee, to be


                                      -16-



              negotiated by the Parties, as compensation to ACT for GTC's use
              of such manufacturing rights.
     
8.  Confidential Information.

    8.1. Nondisclosure of Confidential Information.  Neither party shall
         directly or indirectly publish, disseminate or otherwise disclose,
         deliver or make available to any person outside its organization any
         of the other Party's Confidential Information.  Each Party may
         disclose the other Party's Confidential Information to persons within
         its organization and to its Affiliates which have a need to receive
         such Confidential Information in order to further the purposes of this
         Agreement and who/which are bound to protect the confidentiality of
         such Confidential Information, as set forth in Section 8.3, below. 
         Each Party may disclose the other Party's Confidential Information to
         a governmental authority or by order of a court of competent
         jurisdiction, provided that such disclosure is subject to all
         applicable governmental or judicial protection available for like
         material and reasonable advance notice is given to the other Party.

    8.2. Use of Confidential Information.  Each Party shall use the other
         Party's Confidential Information solely for the purposes contemplated
         in this Agreement or for such other purposes as may be agreed upon by
         the Parties in writing.

    8.3. Agreements with Personnel and Third Parties.  The Parties have or
         shall obtain agreements with all personnel and third parties who will
         have access to the other Party's Confidential Information which impose
         comparable confidentiality obligations as are set forth in this
         Agreement on such personnel and third parties.

9.  Warranties and Indemnity.

    9.1. Warranty by ACT.  ACT represents and warrants to GTC that, with
         respect to the hSA and other proteins/products produced by or on
         behalf of ACT under this Agreement, and the Transgenic Cattle which
         produce such hSA and other proteins/products:

         a.   ACT shall have the unrestricted right to transfer good and
              marketable title to such proteins/products, the milk containing
              such proteins/products and/or the Transgenic Cattle in which such
              proteins/products and milk are produced, to GTC pursuant to this
              Agreement, free and clear of any lien, charge or encumbrance
              created or permitted by ACT;


                                      -17-




         b.   such proteins/products, milk and Transgenic Cattle conform with
              the applicable specifications established by the Liaison
              Committee;

         c.   such proteins/products and milk are not (i) adulterated or
              misbranded within the meaning of the Federal Food, Drug and
              Cosmetic Act, as amended, or within the meaning of any applicable
              state or municipal law in which the definitions of adulteration
              and misbranding are substantially the same as those contained in
              the Federal Food, Drug and Cosmetic Act, as such Act and laws are
              constituted and effective at the time of delivery, or (ii) an
              article which may not be introduced into interstate commerce
              under the provisions of Sections 404, 505 or 512 of such Act, as
              amended;

         d.   such proteins/products, milk and Transgenic Cattle have been
              manufactured in accordance with all current material applicable
              federal, state and local laws and regulations relating to ACT's
              activities under this Agreement, including without limitation
              applicable GMPs and GAPs; and

         e.   with respect to the ACT Patent Rights and ACT Technology only,
              the commercialization of such proteins/products will not infringe
              the patent or other intellectual property rights of any third
              party

         ACT further represents and warrants to GTC that the execution of, and
         performance of the transactions contemplated by, this Agreement have
         been approved by the ACT board of directors and will not conflict with
         or result in any breach of any of the terms, conditions or provisions
         of, or constitute a default under, any agreement to which ACT is a
         party or by which ACT is bound.

    9.2. Indemnification by ACT.  ACT agrees to defend, indemnify and hold
         harmless GTC and its Affiliates, agents, directors, officers and
         employees, at ACT's cost and expense, from and against any and all
         losses, costs, liabilities, damages, fees and expenses, including
         reasonable attorneys' fees and expenses (collectively, "Liabilities")
         incurred in connection with any claim, action or proceeding arising
         out of or in connection with ACT's breach of this Agreement,
         including, without limitation, the warranties set forth herein,
         regardless of the form in which any such claim is made; provided that
         such defense and indemnification shall not apply to the extent that
         the existence or incurrence of any such Liabilities is attributable to
         any negligence or willful misconduct of, or material breach of this
         Agreement by, GTC.

    9.3. Indemnification by GTC.  GTC agrees to defend, indemnify and hold
         harmless ACT and its Affiliates, agents, directors, officers and


                                      -18-




         employees, at ACT's cost and expense, from and against any and all
         Liabilities incurred in connection with any claim, action or
         proceeding arising out of or in connection with (a) the making, using,
         development, testing, registration, distribution, and/or sale of any
         proteins/products produced by ACT in Transgenic Cattle under this
         Agreement or (b) GTC's breach of this Agreement, regardless of the
         form in which any such claim is made; provided that such defense and
         indemnification shall not apply to the extent that the existence or
         incurrence of any such Liabilities is attributable to any negligence
         or willful misconduct of, or material breach of this Agreement by,
         ACT.

    9.4. Limitation of Liability.  Neither Party will be liable for any 
         indirect, incidental, consequential or special damages of any type 
         or kind (including, without limitation, lost profits) arising out of 
         this Agreement, whether any such damages are based on a claim of 
         negligence, strict liability, breach of warranty or otherwise.

    9.5. Insurance.  Prior to the commencement of the first Phase I clinical 
         trial of any proteins/products produced in Transgenic Cattle 
         developed by ACT under this Agreement, each Party shall obtain and 
         maintain, at all times during the term of this Agreement, general 
         liability insurance with appropriate bodily injury, death and 
         property damage limits.  Upon request, a Party shall furnish a 
         certificate of insurance signed by an authorized representative of 
         its insurance underwriter evidencing such coverage and providing for 
         at least thirty (30) days prior written notice of any cancellation, 
         termination or reduction of coverage.

    9.6. Indemnification Claims.  Each Party shall give the other Party prompt
         notice of any claim for which indemnification under this Section 9 is
         or may be applicable.  The indemnifying Party shall be required to
         provide and be entitled to control the defense of any claim covered
         hereunder with counsel reasonably satisfactory to the other Party
         which may, at its own expense, participate in the defense of any claim
         after the indemnifying Party assumes control of the defense thereof.


10. Term and Termination.

   10.1. Term.  The term of this Agreement shall commence on the Effective 
         Date and shall continue indefinitely unless terminated as provided 
         in this Section 10.

   10.2. Termination for Breach.  Each Party shall be entitled to terminate 
         this Agreement by written notice to the other Party in the event 
         that the other Party shall be in default of any of its material 
         obligations hereunder, and shall fail to remedy any such default 
         within sixty (60) days after notice thereof by the

                                      -19-




         non-breaching Party.  Any such notice shall specifically state that  
         the non-breaching Party intends to terminate this Agreement in the 
         event that the breaching Party shall fail to remedy the default. 
         Upon any termination of this Agreement pursuant to this Section 10.2, 
         neither Party shall be relieved of any obligations incurred 
         prior to such termination, including, without limitation, royalty 
         payments and payment for work undertaken by ACT but not yet paid by 
         GTC according to the terms of this Agreement.

   10.3. Survival of Obligations; Return of Confidential Information. 
         Notwithstanding any termination of this Agreement, the obligations 
         of the Parties under Sections 7.1, 7.2, 7.3, 7.4, 7.5, , 7.8, 7.9, 
         7.10(b),  8,  9,  10 and 11, as well as under any other provisions 
         which by their nature are intended to survive any such termination, 
         shall survive and continue to be enforceable.  Upon any termination 
         of this Agreement pursuant to Section 10.2 hereof, each Party shall 
         promptly return to the other Party all written Confidential 
         Information, and all copies thereof, of the other Party.

11. Miscellaneous.

   11.1. Publicity.  Neither Party, nor any of its Affiliates, shall 
         originate any publicity, news release or other public announcement, 
         written or oral, relating to this Agreement or the existence of an 
         arrangement between the Parties, without the prior written approval 
         of the other Party, which approval shall not be unreasonably 
         withheld, except as otherwise required by law.  It is expressly 
         understood that nothing in this Section 11.1 shall prevent a Party 
         from making a disclosure in connection with any required filings 
         with the Securities and Exchange Commission or in connection with 
         the offering of securities or any financing.

   11.2. No Implied Licenses.  No implied licenses are granted pursuant to 
         the terms of this Agreement.  No license rights shall be created by 
         implication or estoppel.

   11.3. No Agency.  Nothing herein shall be deemed to constitute either 
         Party as the agent or representative of the other Party, or both 
         Parties as joint venturers or partners for any purpose.  Each Party 
         shall be an independent contractor, not an employee or partner of 
         the other Party, and the manner in which each Party renders its 
         services under this Agreement shall be within its sole discretion.  
         Neither Party shall be responsible for the acts or omissions of the 
         other Party, and neither Party will have authority to speak for, 
         represent or obligate the other Party in any way without prior 
         written authority from the other Party.

   11.4. Notice.  All notices required under this Agreement to be given by 
         one Party to the other shall be in writing and shall be given by 
         addressing the same to the other at the address or facsimile

                                      -20-



         number set forth below, or at such other address or facsimile number 
         as either may specify in writing to the other.  All notices shall 
         become effective three (3) days after deposit in the United States 
         Mail with proper postage for first class registered or certified 
         mail prepaid, return receipt requested, or if promptly confirmed by 
         mail as provided above, when dispatched by facsimile.

              GTC: Genzyme Transgenics Corporation
                   Five Mountain Road
                   Framingham, Massachusetts 01701-9322
                   Telecopier (508) 370-3793
                   Attn: Vice President and General Counsel

              ACT: Advanced Cell Technology, Inc.
                   One Innovation Drive
                   Worcester, Massachusetts 01605
                   Telecopier: (508) 756-0931
                   Attn: President and CEO

   11.5. Assignment.  This Agreement, and the rights and obligations 
         hereunder, may not be assigned or transferred, in whole or in part, 
         by either Party without the prior written consent of the other 
         Party, except that (a) either Party may assign this Agreement to an 
         Affiliate, provided that such Party remains primarily liable and/or 
         responsible for the performance of such obligations and such 
         Affiliate, and provided further that such Affiliate agrees to be 
         bound to the terms and conditions of this Agreement and (b) either 
         Party may transfer this Agreement in connection with the merger, 
         consolidation or sale of all or substantially all of that Party's 
         assets.

   11.6. Force Majeure.  Except with respect to the payment of monies due 
         hereunder, and the responsibility to maintain the Confidential 
         Information in confidence, neither Party shall be responsible for 
         failure to perform hereunder or for any loss or damage due to causes 
         beyond its reasonable control, including, but not limited to, 
         governmental requirements, inability to obtain required export 
         licenses, work stoppages, fires, civil disobedience, embargo, war, 
         riots, rebellions, earthquakes, strikes, floods, water and the 
         elements, inability to secure equipment, raw materials or transport, 
         acts of God, and similar occurrences. Performance shall be resumed 
         as soon as possible after the cessation of such cause.  Notice to 
         this effect ("Notice of Force Majeure") shall be given in a manner 
         prescribed in Section 11.4 hereof at once to the other Party.  The 
         existence of such causes of delay shall justify the suspension of 
         performance hereunder by either party and shall extend the time for 
         such performance for a period equal to the period of delay; provided 
         however, that if such period of delay shall exceed ninety (90) days 
         from the

                                      -21-




         receipt of Notice of Force Majeure, either Party may terminate this 
         Agreement upon written notification to the other.

   11.7. Non-Solicitation. During the Term of this Agreement and for a period 
         of one (1) year thereafter, neither Party may solicit any person who 
         is employed by or a consultant to the other Party or any Affiliate 
         of such Party to terminate such person's employment by or 
         consultancy to such Party or such Affiliate.  As used herein, the 
         term "solicit" shall include, without limitation, requesting, 
         encouraging, assisting or causing, directly or indirectly, any such 
         employee or consultant to terminate such person's employment with or 
         consultancy to such Party or Affiliate.

   11.8. Entire Agreement.  This Agreement constitutes the entire agreement 
         of the Parties with regard to its subject matter, and supersedes all 
         previous written or oral representations, agreements and 
         understandings between the Parties.  The parties acknowledge and 
         agree that there are no representations, warranties, arrangements, 
         promises or agreements outstanding between them, whether oral or in 
         writing, other than those contained or referred to in this Agreement.

   11.9. No Modification.  This Agreement may be changed only by a writing 
         signed by the Parties.

  11.10. Headings.  The headings contained in this Agreement are for 
         convenience of reference only and shall not be considered in 
         construing this Agreement.

  11.11. Waiver.  The waiver by either Party of a breach or a default of any 
         provision of this Agreement by the other Party shall not be 
         construed as a waiver of any succeeding breach of the same or any 
         other provision, nor shall any delay or omission on the part of 
         either Party to exercise or avail itself of any right, power or 
         privilege that it has or may have hereunder operate as a waiver of 
         any right, power, or privilege by such Party.

  11.12. Severability.  In the event that any one or more of the provisions 
         contained in this Agreement shall, for any reason, be held to be 
         invalid, illegal or unenforceable in any respect, such invalidity, 
         illegality or unenforceability shall not affect any other provisions 
         of this Agreement, and all other provisions shall remain in full 
         force and effect.  If any of the provisions of this Agreement is 
         held to be excessively broad or invalid, illegal or unenforceable in 
         any jurisdiction, it shall be reformed and construed by limiting and 
         reducing it so as to be enforceable to the maximum extent permitted 
         by law in conformance with its original intent.

                                      -22-




  11.13. Successors and Assigns.  This Agreement shall be binding upon and 
         inure to the benefit of the Parties hereto and their successors and 
         permitted assigns.
    
  11.14. Counterparts.  This Agreement may be executed in any number of 
         counterparts, each of which shall be deemed an original but all of 
         which together shall constitute one and the same instrument.

  11.15. Dispute Resolution.  In the event the Parties are unable to resolve 
         any issue which properly comes before it within sixty (60) days, 
         senior executives from each of GTC and ACT shall meet promptly 
         following a notice from either Party in order to discuss and 
         resolve, within sixty (60) days, the outstanding issues facing the 
         Parties.  If  GTC and ACT fail to reach agreement during this sixty 
         (60) day period, the senior executive representatives of GTC and ACT 
         shall meet promptly with a mediator acceptable to GTC and ACT in 
         order to continue to discuss and resolve the outstanding issues 
         facing GTC and ACT. The costs of such mediation will be borne 
         equally by the Parties. Thereafter, any dispute which remains 
         unresolved by the Parties shall be resolved by arbitration in New 
         York City, New York in accordance with the Commercial Rules of 
         Arbitration of the American Arbitration Association. 

  11.16. Applicable Law.  This Agreement shall in all events and for all 
         purposes be governed by, and construed in accordance with, the law 
         of The Commonwealth of Massachusetts without regard to any choice of 
         law principle that would dictate the application of the law of 
         another jurisdiction.

                        -23-




         IN WITNESS WHEREOF, duly-authorized representatives of the parties
have signed this Agreement as of the Effective Date.

GENZYME TRANSGENICS CORPORATION                  

By  /s/ Michael W. Young               
    ---------------------

Print Name: Michael W. Young

Title  Vice President, Commercial Development    
       ---------------------------------------
       duly authorized

ADVANCED CELL TECHNOLOGY, INC.

By  /s/ Steve Parkinson      
    --------------------

Print Name: Steve Parkinson

Title:  President                 
       ----------------
        duly authorized





                                      -24-




                                      Schedule A
                                  ACT Patent Rights


                                       Serial No./         Filing Date/
Title              1st Inventor        Patent No.          Grant Date

Cultured inner     Stice, Steven       US 08/626,054       April 1, 1996
cell mass cell
lines derived
from ungulate                          PCT/US97/04736      March 24, 1997
embryos            
    
Embryonic or       Robl, James         US 08/699,040       August 19, 1996
stem-like cell
lines produced
by cross
species nuclear                        PCT/US97/12919      July 28, 1997
transplantation         

[*] 




                                      -25-


*Confidential Treatment has been requested for the marked portion.




                                      Schedule B
                                 hSA Project Summary

[*]
    









                                      -26-


*Confidential Treatment has been requested for the marked portion.