STOCK OPTION AGREEMENT

            AGREEMENT, dated as of June 10, 1996, between BioCoral, Inc., a
Delaware corporation with its principal place of business c/o Stein Riso Haspel
& Jacobs, 805 Third Avenue, New York, NY 10022 (the "Company") and Riccardo
Mortara, with his office at 14 Quai du Seujet, 1201 Geneve, SWITZERLAND (the
"Optionee").

                              W I T N E S S E T H:

            WHEREAS, on June 8, 1996, the Board of Directors of the Company
resolved to grant an option (the "Option") to the Optionee for the purchase of
up to 125,000 shares of the Company's common stock, par value $.001 per share
(the "Common Stock") at a strike price of $7.75 (US) per share on the terms and
conditions hereinafter set forth.

            NOW, THEREFORE, in consideration of the mutual covenants contained
herein, the parties hereto agree as follows:

      1. Grant of Option. Subject to all the terms and conditions hereof, the
Company hereby grants to Optionee the right to purchase all or any part of an
aggregate of 125,000 shares of Common Stock of the Company (the "Option Shares")
at an exercise price of $7.75 per share, on the terms and conditions set forth
in this Agreement.

      2. Exercisability of Option. The Option Shares subject to the Option shall
become purchasable beginning at any time and from time to time beginning on the
date hereof and for a period of 12 months thereafter, and after the expiration
date (the "Expiration Date"), this option and all rights hereunder shall expire
and any Option Shares not purchased on or before the Expiration Date may not
thereafter be purchased hereunder. In the event Optionee fails to exercise the
option on or prior to the Expiration Date, then the Option as to all Option
Shares not exercised shall expire and Optionee shall have no rights with respect
to such remainder of the Option or the Option Shares.

      3. Consideration for Grant of Option. The consideration for grant of the
Option is $10,

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the receipt of which is hereby acknowledged, and Optionee's agreement to serve
as a director of the Company during all or any portion of the Option period.

      4. Method of Exercise of Option; Payment of Option Purchase Price. This
Option shall be exercisable at any time and from time to time, prior to the
Expiration Date, by written notice (the "Notice") to the Company at its
principal office, presently located c/o Stein Riso Haspel & Jacobs LLP, 805
Third Avenue, New York, NY 10022. The Notice shall state the Optionee's election
to exercise this Option and the number of Option Shares in respect of which it
is being exercised, and shall be accompanied by a check in the amount of the
Exercise Price. Upon payment of the full purchase price of the Option Shares by
Optionee, the Company shall deliver a certificate or certificates representing
those shares. A certificate or certificates for the shares as to which this
Option shall have been so exercised shall be registered in the name of the
Optionee and shall be delivered to Optionee at the address of Optionee specified
in the Notice or at such other address as Optionee shall set forth in its
Notice.

      5. Non-Assignability of Option. This Option may be exercised only by the
Optionee and shall not be sold, transferred, assigned, pledged, hypothecated or
otherwise disposed of in any way (whether by operation of law or
otherwise)without the Company's prior written consent except that Optionee may,
solely in connection with a transfer of all or substantially all of his assets
to an entity or entities controlled by Optionee("Affiliate"), sell, transfer or
assign all its interest in this Agreement to such Affiliate but only after
giving the Company at least thirty days notice in writing of the proposed sale,
transfer or assignment. Any buyer, transferee, or assignee of this Option shall
be bound by and subject to each and every provision of this Agreement and shall
not sell, transfer, assign, pledge, hypothecate or otherwise dispose of the
Option in any way (whether by operation of law or otherwise).


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      6. Adjustments to Preserve Option Benefits.

            If the outstanding shares of the Company's Common Stock are
exchanged for a different number or kind of shares or securities of the Company
through stock splits, reverse stock splits, stock dividends, recapitalization or
other changes in the stock of the Company, an appropriate and proportionate
adjustment shall be made in the number and kind of shares issued upon any
subsequent exercise of this Option without any change in the aggregate purchase
price to be paid for such shares. For any and all such purposes, but only for
such purposes, Optionee shall be considered to be a shareholder of record of the
Company as of the date of this Option Agreement. Nothing in this Agreement shall
preclude the Corporation from issuing additional shares of Common Stock to any
third party.

      7. Limitation of Optionee's Rights. Except as otherwise provided in
Section 6 above, Optionee shall not have any of the rights or privileges of a
shareholder of the Company in respect of any Option Shares issuable upon
exercise of this Option unless and until those shares have been paid for in full
and upon such payment in full Optionee shall be deemed to be the record holder.

      8. Purchase for Investment. The Optionee represents and agrees that if the
Optionee exercises this Option in whole or in part then those Option Shares so
acquired will be acquired for the purpose of investment and not with a view to
their resale or distribution and upon each exercise of this Option, the Optionee
will furnish to the Company a written statement to that effect, satisfactory in
form and substance to the Company and its counsel. Optionee understands and
acknowledges that the shares to be acquired pursuant to this Option will be
restricted securities as such term is defined under the Securities Act of 1933,
as amended, (the "Act") and accordingly will bear a legend indicating such
restrictions.


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      9. Representations and Warranties of Optionee. As a condition to receipt
of the Option and for other good and valuable consideration, receipt of which is
hereby acknowledge, the Optionee represents and warrants to the Company as
follows:

                  (i) Optionee acknowledges that the Company is a development
stage company with no significant operating history and that there are
significant risks associated with the Company's business. Accordingly, the value
of the Option and the Option Shares will be based upon the Company's development
of its business which is subject to significant risks; and

                  (ii) Optionee understands that the Option and the Option
Shares (upon exercise of the option) are being offered and sold under an
exemption from registration provided by Section 4(2) of the Act and the
regulations promulgated thereunder, as well as applicable State law exemptions,
and warrants and represents that the Option and the Option Shares are being or
will be (in the case of the Option Shares) acquired by the undersigned solely
for the undersigned's own account, for investment purposes only, and are not
being purchased with the intent or view to resell the Option or the Option
Shares or for the resale, distribution, subdivision or fractionalization
thereof. Consequently, the undersigned must bear the economic risk of the
investment for an indefinite period of time because the Option and the Option
Shares cannot be resold or otherwise transferred unless subsequently registered
under the act and qualified under applicable State law or an opinion of
qualified counsel that indicates an exemption from registration and/or
qualification is available.

      10. Notices. Any notice to be given under the terms of this Option shall
be in writing and addressed to the Company at the Company's then-present
addressor to Optionee at the address provided herein, or at such other address
as either party may hereafter designate in writing to the other. Any notice or
other communication given hereunder shall have been deemed duly given when
enclosed in a properly sealed envelope addressed as aforesaid, registered or
certified, and deposited


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postage prepaid in a post office or branch post office or, in person, when so
delivered, or by Federal Express or similar courier providing evidence of
receipt.

      11. Representations of Company. The Company represents: (i) the execution,
delivery and performance of this Agreement has been duly authorized by the Board
of Directors of the Company; (ii) the consummation of the transaction
contemplated by this Agreement will not violate any provision of the Company's
Certificate of Incorporation or Bylaws; and (iii) no consent of any third party
including, without limitation, federal or state regulatory agencies is required
for execution and performance of this Agreement by the Company.

      12. Governing Law. This Agreement shall be deemed to be made under and
shall be construed in accordance with the laws of the State of Delaware and
applicable Federal law without regard to conflict of law principles.

      13. Successors and Assigns. This Agreement shall be binding upon and inure
to the benefit of the parties hereto and their legal successors and assigns.

      14. Entire Understanding. This Agreement constitutes the entire
understanding of the parties and shall not be amended except by written
agreement between the parties.

            IN WITNESS WHEREOF, the parties hereto have executed this Agreement
as of the day and year first above written.

                                      BIOCORAL, INC.

                                      By: /s/ Nasser Nassiri
                                         ----------------------------
                                         Nasser Nassiri, Secretary

                                          /s/ Riccardo Mortara
                                         ----------------------------
                                            Riccardo Mortara


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