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                                                                  EXHIBIT 10.10

1. As adopted by the Board of Directors on May 11, 1993 and approved by the
   stockholders on June 25, 1993.

2. As amended by the Board of Directors on March 3, 1997, [and approved by
   the stockholders on May 28, 1997].

                        GENZYME TRANSGENICS CORPORATION

                        1993 Director Stock Option Plan

    The purpose of this 1993 Director Stock Option Plan (the "Plan") of Genzyme
Transgenics Corporation (the "Company") is to attract and retain highly
qualified non-employee directors of the Company and to encourage ownership of
stock of the Company by such Directors so as to provide additional incentives to
promote the success of the Company.

1. Administration of the Plan.

    Grants of stock options under the Plan shall be automatic as provided in
Section 6. However, all questions of interpretation with respect to the Plan and
options granted under it shall be determined by the Board of Directors of the
Company (the "Board") or by a committee consisting of one or more directors
appointed by the Board and such determination shall be final and binding upon
all persons having an interest in the Plan.

2. Persons Eligible to Participate in the Plan.

    All directors of the Company who are not employees of the Company or of any
subsidiary of the Company shall be eligible to participate in the Plan, unless
such director irrevocably elects not to participate.

3. Shares Subject to the Plan.

    (a) The aggregate number of shares of the Company's Common Stock which may
be optioned under this Plan is 100,000 shares. Shares issued under the Plan may
consist in whole or in part of authorized but unissued shares or treasury
shares.

    (b) In the event of a stock dividend, split-up, combination or
reclassification of shares, recapitalization or other similar capital change
relating to the Company's Common Stock, the maximum aggregate number and kind of
shares or securities of the Company as to which options may be granted under
this Plan and as to which options then outstanding shall be exercisable, and the
option price of such options shall be appropriately adjusted so that the
proportionate number of shares or other securities as to which options may be
granted and the proportionate interest of holders of outstanding options shall
be maintained as before the occurrence of such event.

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    (c) In the event of a consolidation or merger of the Company with another
corporation where the Company's stockholders do not own a majority in interest
of the surviving or resulting corporation, or the sale or exchange of all or
substantially all of the assets of the Company, or a reorganization or
liquidation of the Company, any deferred exercise period shall be automatically
accelerated and each holder of an outstanding option shall be entitled to
receive upon exercise and payment in accordance with the terms of the option the
same shares, securities or property as he would have been entitled to receive
upon the occurrence of such event if he had been, immediately prior to such
event, the holder of the number of shares of Common Stock purchasable under his
or her option; provided, however, that in lieu of the foregoing the Board may
upon written notice to each holder of an outstanding option or right under the
Plan, provide that such option or right shall terminate on a date not less than
20 days after the date of such notice unless theretofore exercised.

    (d) Whenever options under this Plan lapse or terminate or otherwise become
unexercisable the shares of Common Stock which were subject to such options may
again be subjected to options under this Plan. The Company shall at all times
while this Plan is in force reserve such number of shares of Common Stock as
will be sufficient to satisfy the requirements of this Plan.

4. Non-Statutory Stock Options.

    All options granted under this Plan shall be non-statutory options not
entitled to special tax treatment under Section 422 of the Internal Revenue Code
of 1986, as amended (the "Code").

5. Form of Options.

    Options granted hereunder shall be in such form as the Board or any
committee appointed pursuant to Section 1 above may from time to time determine.

6. Grant of Options and Option Terms.

    (a) Automatic Grant of Options. Upon the adoption of this Plan and upon each
subsequent initial election of any eligible director to the Board prior to the
Company's 1994 annual meeting of its stockholders and upon the election or
re-election of any eligible director at each annual meeting of the stockholders
thereafter, each such director shall automatically be granted options to
purchase 2,000 shares of Common Stock for each year of the term of office to
which he or she is elected. In addition, upon the election of a director who is
eligible to receive options to purchase Common Stock under the Plan other than
at an annual meeting of stockholders (whether by the Board or the stockholders
and whether to fill a vacancy or otherwise), such director shall automatically
be granted options to purchase 2,000 shares of Common Stock for each year or
portion thereof of the term of office to which he or she is elected. No options
shall be granted hereunder after ten years from the date on which this Plan was
initially approved and adopted by the Board.

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    (b) Date of Grant. The "Date of Grant" for options granted under this Plan
shall be the date of election or re-election as a director, as the case may be.

    (c) Option Price. The option price for each option granted under this Plan
shall be the current fair market value of a share of Common Stock of the Company
as determined (i) prior to date on which the Company becomes subject to the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), by the Board
in good faith or in the manner established by the Board from time to time, and
(ii) on or after the date on which the Company is subject to the Exchange Act,
by the last sale price for the Company's Common Stock as reported by the
National Association of Securities Dealers Automated Quotations National Market
System for the business day immediately preceding the Date of Grant.

    (d) Term of Option. The term of each option granted under this Plan shall be
ten years from the Date of Grant.

    (e) Exercisability of Options. Options granted under this Plan shall become
exercisable with respect to 2,000 shares on the Date of Grant and on each annual
meeting of stockholders of the Company following the Date of Grant if and only
if the option holder is a member of the Board at the opening of business on that
date (i.e., options to purchase 6,000 shares of Common Stock granted at the 1994
annual meeting will become exercisable with respect to 2,000 shares at each of
the 1994, 1995 and 1996 annual meetings).

    (f) General Exercise Terms. Directors holding exercisable options under this
Plan who cease to serve as members of the Board may, during their lifetime,
exercise the rights they had under such options at the time they ceased being a
director for the full unexpired term of such option. Any rights that have not
yet become exercisable shall terminate upon cessation of membership on the
Board. Upon the death of a director, those entitled to do so shall have the
right, at any time within twelve months after the date of death, to exercise in
whole or in part any rights which were available to the director at the time of
his or her death. The rights of the option holder may be exercised by the
holder's guardian or legal representative in the case of disability and by the
beneficiary designated by the holder in writing delivered to the Company or, if
none has been designated, by the holder's estate or his or her transferee on
death in accordance with this Plan, in the case of death. Options granted under
the Plan shall terminate, and no rights thereunder may be exercised, after the
expiration of the applicable exercise period. Notwithstanding the foregoing
provisions of this section, no rights under any options may be exercised after
the expiration of ten years from their Date of Grant.

    (g) Method of Exercise and Payment. Options may be exercised only by written
notice to the Company at its head office accompanied by payment of the full
option price for the shares of Common Stock as to which they are exercised. The
option price shall be paid in cash or by check or in shares of Common Stock of
the Company, or in any combination thereof. Shares of Common Stock surrendered
in payment of the option price shall have been held by the person exercising the
option for at least six months, unless otherwise permitted by the Board. The
value of shares delivered in payment of the option price shall be their fair
market value, as determined in accordance with Section 6(c) above, as of the
date of exercise. Upon receipt of such notice and payment, the Company shall
promptly

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issue and deliver to the optionee (or other person entitled to exercise
the option) a certificate or certificates for the number of shares as to which
the exercise is made.

    (h) Limitations on Transferability. Options granted under this Plan shall
not be transferable by the recipient other than by will or the laws of descent
and distribution and are exercisable during such person's lifetime only by such
person or by such person's guardian or legal representative, provided the Board
or any committee appointed by the Board may in its discretion waive such
restriction in any case.

7. Limitation of Rights.

    (a) No Right to Continue as a Director. Neither the Plan, nor the granting
of an option or any other action taken pursuant to the Plan, shall constitute an
agreement or understanding, express or implied, that the Company will retain an
option holder as a director for any period of time or at any particular rate of
compensation.

    (b) No Stockholders' Rights for Options. A director shall have no rights as
a stockholder with respect to the shares covered by options until the date the
director exercises such options and pays the option price to the Company, and no
adjustment will be made for dividends or other rights for which the record date
is prior to the date such option is exercised and paid for.

8. Amendment or Termination.

    The Board may amend or terminate this plan at any time.  The Board may amend
or modify any outstanding option in any respect, provided that the optionee's
consent to such action shall be required unless the Board determines that the
action, taking into account any relative action, would not materially and
adversely affect the optionee.

9. Stockholder Approval.

    This Plan was approved by the Stockholders on June 25, 1993 and the
amendments approved by the Board of Directors on March 3, 1997 and any further
amendments hereto shall be subject to stockholder approval to the extent (i)
required by law, (ii) required by Nasdaq or stock exchange listing requirements,
as determined by the Board of Directors, or (iii) as desirable, as determined by
the Board of Directors, to comply with Rule 16b-3 under the Securities Exchange
Act of 1934, as amended. In the event any approval is not obtained, all options
granted under this Plan after such further amendment shall be void and without
effect.

10. Governing Law.

    This Plan shall be governed by and interpreted in accordance with the laws
of the Commonwealth of Massachusetts.

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