AMENDMENT #3 TO REVOLVING CREDIT AGREEMENT
                       ------------------------------------------

      THIS AMENDMENT #3 TO THE REVOLVING CREDIT AGREEMENT  is made as of
February 1, 2001 and hereby amends that certain Revolving Credit Agreememt dated
January 31, 1997 and Amendment #1 dated August 31, 1997, and Amendment #2 dated
February 1, 1999  by and between Hydrogel Design Systems, Inc., a Delaware
corporation (the "Borrower"), and Embryo Development Corporation, a Delaware
corporation (the "Lender").

                                    WITTNESETH
                                   -----------

     WHEREAS, the Borrower and Lender are parties to that certain Revolving
Credit Agreement dated January 31, 1997, Amendment dated August 31, 1997 and
Amendment dated February 1, 1999; and

     WHEREAS, the Borrower and Lender desire to futher amend that certain
Revolving Credit Agreement to effect the changes provided for herein.

     NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein, the receipt and sufficiency of which is hereby acknowledged,
the parties hereto agree as follows:


      1.Effective as of the date hereof, Section 1.1 is hereby amended to read
        as follows:

       "Termination Date" shall mean September 30, 2002, twenty (20) months
        following the date of this Amendment #3.

        Effective as of the date hereof, Section 2.8 is hereby amended as
        follows:

        Maturity of Loans and Required Payment of Principal and Interest.
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        The outstanding principal amount, and any accrued interest, shall be due
        and payable as follows: (i) Fifty (50) % of any cash flow from
        operations of Borrower  (as defined by generally accepted accounting
        principles)  in excess of $500,000 during any fiscal year of Borrower
        which ends prior to the Termination Date shall be required to be paid to
        Lender.  Such payment shall be made within 45 days of the fiscal year
        end of Borrower and; (ii) any remaining outstanding principal and
        interest balance due shall be payable on September 30, 2002.

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       2.This Amendment #3 shall be governed by and construed in accordance with
       the laws of the State of New York, without regard to principles of
       conflicts of law.

      3.Except as otherwise specifically set forth herein, all of the terms and
      provisions of the Revolving Credit Agreement and prior Amendments shall
      remain in full force and effect.


     IN WITNESS WHEREOF, the parties hereto have caused this Amendment #3 to
the Revolving Credit Agreement to be duly executed and delivered by their proper
and duly authorized officers as of the day and year first above written.


                              HYDROGEL DESIGN SYSTEMS, INC.


                              BY: /s/ Karen Nazzareno
                             __________________________

                             NAME:  Karen Nazzareno

                             TITLE: CFO



                              EMBRYO DEVELOPMENT CORPORATION


                              BY: /s/ Matthew Harriton
                             ___________________________

                              NAME: Matthew Harriton

                              TITLE:  CEO