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                                                              Exhibit 10.49.7

                                UNCONDITIONAL GUARANTY

KNOW ALL MEN BY THESE PRESENTS:   

    For a valuable consideration and specifically for the purpose of inducing 
Simmons First National Bank, a national banking institution, ("Lender") to 
loan and to continue to loan funds to TSI Redfield Laboratories, Inc., an 
Arkansas corporation ("Borrower"), the undersigned ("Guarantor"), does hereby 
agree for itself, its successors and assigns with and unto the Lender as 
follows:

    1.  Guarantee of Payment.  The Guarantor hereby unconditionally 
guarantees the full and timely payment of all indebtedness of every kind and 
nature of the Borrower to the Lender, direct or indirect, without limit as to 
the amount of such indebtedness, whether now existing or hereinafter 
incurred, whether or not such indebtedness shall be similar or dissimilar, 
related or unrelated to any existing indebtedness, including but not limited 
to an indebtedness evidenced by two promissory notes in the amount of 
$700,000.00 and $350,000.00, of even date herewith (collectively 
"Indebtedness"). 

    2.  Guarantee of Performance. The Guarantor further unconditionally 
guarantees prompt, timely, and complete performance of and compliance by 
Borrower of all the terms and conditions contained in any of the instruments 
and documents, including but not limited to promissory notes, mortgages, 
security agreements, pledges and collateral assignments ("Loan Documents"), 
given in connection with the origination, extension or collection of the 
Indebtedness; the timely payment of all real and personal property taxes, 
special assessments, and premiums for insurance of every kind required under 
the terms of any of the Loan Documents; and generally, the performance of 
each and every other covenant and condition set forth and contained in the 
Loan Documents.

    3.  Waivers of Notice and Additional Authority.  The Guarantor waives 
notice of any default by Borrower upon the Indebtedness or of any transfer of 
the title to any property securing any of the Indebtedness pursuant to any 
Loan Document, and the Lender, or the holder of any note evidencing any of 
the Indebtedness, shall not be required to resort to any collateral other 
than this guaranty or attempt to recover upon the liability of Borrower in 
any way as a condition prerequisite to recovering upon this Guaranty.  The 
Lender and any subsequent holder of any note evidencing any of the the 
Indebtedness, may, without notice to the Guarantor, deal with the Borrower, 
or any one on its behalf or if title to any property shall have been 
transferred, the owner thereof, from time to time with respect to any of the 
Indebtedness and the security therefor in any manner whatsoever, including 
the release of any obligor or of any of the collateral, and Guarantor hereby 
specifically waives each and every defense predicable upon such dealing 
including, without limitation, the release of any part of the security for 
any of the Indebtedness or any of the obligors thereon, except the defense of 
actual payment in cash on the Indebtedness.      

    4.  Continuation of the Guaranty.  This Guaranty shall continue with 
respect to the Indebtedness, and all continuations, extensions or renewals 
thereof, in favor of the Lender and all subsequent holders of any note 
evidencing any of the Indebtedness, notwithstanding that the


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Borrower shall have conveyed its title and notwithstanding that other 
obligors may have assumed or guaranteed payment.  It is understood and agreed 
that this Guaranty shall, in all respects, run in favor of the holders of any 
note evidencing any of the Indebtedness and notice to the Guarantor of any 
transfer, endorsement or assignment of any such note shall not be required.

    5.  Waiver of Acceptance.  The Guarantor further waives notice of the 
acceptance of this Guaranty by the Lender and presentment, demand, notice of 
nonpayment, notice of extension of the time of payment or of any dealings 
with any obligor or any collateral.

    6.  Additional Covenants of Guarantor.  The Guarantor agrees that the 
liability of the Guarantor hereunder shall not in anyway be released, 
diminished, impaired, reduced, or affected by:

    (a)  The taking or accepting of any other security or guaranty for any or 
all of the Indebtedness;

    (b)  Any release, withdrawal, surrender, exchange, substitution, 
subordination, or loss of any security or other guaranty at any time existing 
in connection with any or all of the Indebtedness; any partial release of the 
liability of any other Guarantor hereunder or under any of the Loan Documents 
had, or to be had, in connection with, or as security for, any of the 
Indebtedness, or the corporate dissolution, insolvency, bankruptcy, 
disability, or lack of authority of Borrower, Guarantor, or any other 
guarantor or any party at any time liable for the payment of any or all of 
the Indebtedness, whether now existing or hereafter occurring;

    (c)  Any renewal, extension, modification, or rearrangement of the 
payment of any or all of the Indebtedness, or the performance of any covenant 
contained in any Loan Document had, or to be had, in connection with, or as 
security for, the Indebtedness, either with or without notice to, or consent 
of, such Guarantor or any adjustment, indulgence, forbearance, or compromise 
that may be granted or given by Lender to any party; or

    (d)  Any neglect, delay, omission, failure, or refusal of Lender to take 
or prosecute any action for the collection of any of the Indebtedness or to 
foreclose or take or prosecute any action in connection with any lien, right, 
or security existing or to exist in connection with, or as security for, any 
of the Indebtedness; or to take any action hereunder; it being the intention 
hereof that Guarantor shall remain liable as principal until the full amount 
of the Indebtedness, together with interest, and any other sums due or to 
become due upon or in connection with any of the same, shall have been fully 
paid, performed and observed by Borrower.

    IN WITNESS WHEREOF, the undersigned has caused these presents to be 
executed this 22nd day of May, 1997.

                             GENZYME TRANSGENICS CORPORATION

                             By  /s/ John B. Green, Vice President  
                                ------------------------------------
                                  John B. Green, Vice President