Filed by Biomatrix, Inc. (Commission File No. 001-14221)
                           Pursuant to Rule 425 under the Securities Act of 1933
                                        and deemed filed pursuant to Rule 14a-12
                                          of the Securities Exchange Act of 1934


         Subject Companies: Genzyme Corporation (Commission File No. 000-14680),
            Biomatrix, Inc. and Genzyme Corporation's Surgical Products Division
                                                      and Tissue Repair Division


FOR BIOMATRIX:                                   FOR GENZYME:
Endre Balazs, M.D., CEO                          Sally Curley (investors)
Rory Riggs, President                            617-591-7140
Anne Marie Fields, Investor Relations            Kristen Nally (GZTR investors)
201-945-9550                                     617-252-7815
                                                 Kim Witkop (GZSP investors)
                                                 617-761-8563
                                                 Bo Piela (media)
                                                 617-252-7785

FOR IMMEDIATE RELEASE
April 18, 2000


       GENZYME AND BIOMATRIX FILE PROXY STATEMENT FOR GENZYME BIOSURGERY

         CAMBRIDGE, Mass. and RIDGEFIELD, N.J.--Genzyme Corp. and Biomatrix Inc.
today filed a joint proxy statement/prospectus with the Securities and Exchange
Commission for the planned formation of Genzyme Biosurgery, a new Genzyme
division with its own newly created stock. Genzyme Biosurgery will combine the
businesses of Biomatrix (NYSE: BXM), Genzyme Tissue Repair (Nasdaq: GZTR), and
Genzyme Surgical Products (Nasdaq: GZSP).

         The merger will create the foremost company in biosurgery, a rapidly
emerging market in which sophisticated biomaterials and biological products are
used to enhance or replace conventional surgical and medical procedures.

         Genzyme and Biomatrix said today that the transaction, announced March
6, is on schedule to close by the end of June 2000, pending regulatory and
shareholder approvals. The companies expect to mail the joint proxy
statement/prospectus to their shareholders by mid-May. On March 22, Genzyme and
Biomatrix filed a notification of merger with the Department of




Justice and the Federal Trade Commission, as required under the
Hart-Scott-Rodino Anti-Trust Improvements Act.

         A special meeting of Genzyme shareholders to vote on proposals related
to the creation of Genzyme Biosurgery will be held in June in Cambridge, Mass. A
special meeting of Biomatrix shareholders will be held in June in Ridgefield,
N.J., and will replace the annual meeting of Biomatrix shareholders originally
scheduled for May.

         The formation of Genzyme Biosurgery will require shareholders of each
of Genzyme's four divisions, voting together as a single class, to approve a
charter amendment creating the Genzyme Biosurgery stock and eliminating the
Genzyme Tissue Repair and Genzyme Surgical Products stocks. In addition, Genzyme
Tissue Repair and Genzyme Surgical Products shareholders each must approve the
transfer of their respective assets and property into Genzyme Biosurgery and the
conversion of all outstanding shares of their respective stocks into shares of
Genzyme Biosurgery stock. Biomatrix shareholders must approve the merger with
Genzyme.

         The boards of directors of both Genzyme Corp. and Biomatrix have
unanimously approved the merger. Dr. Endre Balazs and three other executive
officers of Biomatrix have agreed to vote their Biomatrix shares, totaling
approximately 37 percent of the outstanding shares, in favor of the transaction.

WHAT SHAREHOLDERS WILL RECEIVE

         Under the terms of a definitive merger agreement, Genzyme Biosurgery
will be formed by combining Genzyme Tissue Repair and Genzyme Surgical Products
in tax-free stock-for-stock exchanges to form one unit, which will merge with
Biomatrix in an exchange of stock and cash.


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         Genzyme Tissue Repair shareholders will receive 0.3352 of a share and
Genzyme Surgical Products shareholders will receive 0.6060 of a share of Genzyme
Biosurgery stock for each share of their stock.

         Under the merger agreement, Genzyme has agreed to pay cash at $37 per
share for up to 28.38 percent of the outstanding shares of Biomatrix common
stock and to exchange Genzyme Biosurgery stock on a one-for-one basis for 71.62
percent of the outstanding shares of Biomatrix common stock. The cash portion of
the merger consideration is limited to approximately $245 million and may be
reduced to accommodate the exercise of appraisal rights, and for tax purposes,
to assure that at least 45 percent of the total consideration is Genzyme
Biosurgery stock.

         Biomatrix will send its shareholders an election form on which they
will be able to indicate their preference for cash, stock, or the standard
consideration - a fixed combination of cash and stock. Assuming no adjustment to
the aggregate cash consideration occurs, Biomatrix shareholders who select the
standard consideration will receive $32 in cash for 28.38 percent of their
Biomatrix shares and will receive one share of Genzyme Biosurgery stock for one
share of Biomatrix stock for 71.62 percent of their Biomatrix shares.

         If Biomatrix shareholders elect to receive cash for more than the
available cash consideration, the amount of cash distributed to shareholders who
make cash elections will be reduced on a prorated basis and offset with shares
of Genzyme Biosurgery. Conversely, if Biomatrix shareholders elect to receive
more shares of Genzyme Biosurgery stock than are available, the number of shares
of Genzyme Biosurgery stock distributed to shareholders who make stock elections
will be reduced on a prorated basis and offset with cash. Therefore, the
consideration received by a Biomatrix shareholder may differ from the
shareholder's expressed preference.


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         Upon completion of the merger, Biomatrix shareholders will own
approximately 47 percent of Genzyme Biosurgery, Genzyme Tissue Repair
shareholders will own approximately 27 percent, and Genzyme Surgical Products
shareholders will own approximately 26 percent.

         Upon formation, Genzyme Biosurgery will have approximately 35 million
shares outstanding. Genzyme has applied for the shares to trade on the Nasdaq
National Market under the symbol GZBX following the completion of the merger.

ABOUT GENZYME BIOSURGERY

         The combination of Biomatrix, Genzyme Tissue Repair, and Genzyme
Surgical Products will create a self-sustaining enterprise with substantial
financial resources. Genzyme Biosurgery will market a robust portfolio of 24
products focused primarily on bio-orthopedics and cardiothoracic surgery, two
biosurgical areas with high growth potential. It will also unite companies with
powerful scientific capabilities and nearly 40 years of combined leadership in
the development and commercialization of unique biomaterials based on
hyaluronan.

         Genzyme Biosurgery had pro forma revenues of approximately $212 million
for 1999. In 2000, it is expected to generate pro forma revenues of
approximately $250 million and to invest over $45 million in research and
development to support a robust product pipeline. In 2001, Genzyme Biosurgery is
expected to be profitable on a cash-earnings-per-share basis, before
amortization of goodwill, and should generate cash flow from operations
sufficient to support current operations and to service any debt associated with
the acquisition of Biomatrix.

         Genzyme Biosurgery will have over 1300 employees; six dedicated
manufacturing facilities; global clinical and regulatory capabilities; an
extensive intellectual property portfolio; several established sales
organizations in focused surgical markets; and valuable marketing and
distribution agreements with a number of large, multi-national health care
companies.


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         Genzyme Biosurgery will be composed of Biomatrix, a worldwide leader in
the development and manufacture of viscoelastic biomaterials for use in
orthopedic and other medical applications; Genzyme Tissue Repair, a leading
developer of biological products for the treatment of orthopedic injuries and
severe burns; and Genzyme Surgical Products, which develops and markets
mechanical devices, biomaterials, and biotherapeutics for cardiothoracic and
other surgical markets, and is a leader in developing biomaterials to prevent
post-surgical adhesions. As a division of Genzyme Corp., Genzyme Biosurgery will
have its own common stock intended to reflect its value and track its economic
performance.

         This press release contains forward-looking statements, including
statements concerning the formation of Genzyme Biosurgery and the consummation
of the merger with Biomatrix, the creation of a new publicly traded stock for
Genzyme Biosurgery, the future growth and success of Genzyme Biosurgery and
Genzyme Biosurgery's products, the sufficiency of the cash and other resources
of Genzyme Biosurgery and the future revenues and profitability of Genzyme
Biosurgery. Actual results may differ materially depending on many factors
including the accuracy of information about the biosurgery market, the
competitive environment for the biosurgery market, market acceptance of Genzyme
Biosurgery's products and services, the enrollment rate for clinical trials, the
ability to successfully complete preclinical and clinical development of
products, the actual safety and efficacy of products, the timing and content of
submissions to and decisions by the FDA and other regulatory authorities,
conditions in the financial markets relevant to the proposed creation of Genzyme
Biosurgery, the likelihood of regulatory and other approvals of the
transactions, the operational integration associated with the transactions and
other risks generally associated with transactions.

                                      # # #

For additional information about the creation of Genzyme Biosurgery, investors
may consult the Questions & Answers document located on the Web sites of Genzyme
(http://www.genzyme.com) and Biomatrix at (http://www.biomatrix.com.) This
document will be updated from time to time as new information becomes available.

Investors are also urged to read the joint proxy statement/prospectus relating
to this transaction filed with the Securities and Exchange Commission because it
will contain important information. The joint proxy statement/prospectus and
other documents filed by Genzyme and Biomatrix with the commission may be
obtained for free at the commission's Web site (www.sec.gov) and from Genzyme or
Biomatrix. Requests to Genzyme may be directed to Sally Curley, or you can
access documents on the company's Web site. Requests to Biomatrix should be
directed to Anne Marie Fields, or you can access documents on the company's Web
site.


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Due to the proposed transaction, Biomatrix will not be mailing a traditional
annual report for 1999. An annual report on form 10-K has been filed with the
SEC and is available on Biomatrix' Web site, or is available at no charge by
contacting Biomatrix.



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