<PAGE>

                                                                    Exhibit 10.4

This INDENTURE OF LEASE made as of this 6th day of October 1995 by and between
JOSEPH BIOTTI, JR. AS TRUSTEE OF THE ONE NEVADA REALTY TRUST under a declaration
of trust dated September 14, 1984 and recorded in the Middlesex South Registry
District of the Land Court of The Commonwealth of Massachusetts (hereinafter
referred to as the "Registry") as Document 667,834 (hereinafter called "Lessor")
and MATRITECH, INC., a corporation organized and existing under the laws of the
State of Delaware and having a usual place of business in the City of Cambridge,
County of Middlesex, said Commonwealth (hereinafter called "Lessee")

                                 WITNESSETH THAT

     Lessor, for himself and his successors and assigns, in consideration of the
rents herein reserved and of the agreements, covenants and conditions herein
contained and expressed on the part of Lessee to be kept, performed and
observed/ hereby demises and lets unto Lessee and its legal representatives,
successors and assigns, and Lessee hereby leases from Lessor 22,500 square feet
of space in the building known and numbered as 330 Nevada Street (hereinafter
the "Building") in the City of Newton, said County of Middlesex (the square
footage within the Building being hereinafter referred to as the "Premises" or
"demised premises" and more particularly shown on Exhibit A attached hereto and
made a part hereof). Lessee shall have, as appurtenant to the Premises, rights
to use in common with others the driveways, approaches, parking areas and other
portions of the 94,505 square foot parcel

<PAGE>

of land on which the Building is situated (hereinafter sometimes referred to as
the "Parcel") necessary for access to the Building and areas of the Project (as
hereinafter defined) designated by Lessor for parking, and the common facilities
in the Building and the Parcel on which it is located including without
limitation sidewalks, lobbies, hallways, stairways, entranceways of the
Building, pipes, ducts, conduits, utility lines, wires, sewage system and
appurtenant equipment serving the Premises, and such other areas and facilities
in the Building and the Parcel from time to time intended for general use by
Lessee, other lessees and Lessor.

                                    ARTICLE I

     A. The Term of this lease shall commence on January 1, 1996 or the earliest
first day of a month thereafter when a certificate of occupancy shall have been
issued by the building inspector of the City of Newton (which date is hereafter
some times referred to as "the date of commencement of the Term") and shall be a
period of five (5) years.

     B. Prior to the date of commencement of the Term, Lessee shall have the
right to use and occupy the Premises pursuant to the terms of that certain
Tenant-At-Will Agreement dated as of August 29, 1995 between the parties hereto
(the "Prior Tenancy Agreement"). Upon execution of this Lease, the Prior Tenancy
Agreement in all respects will be superseded by this Lease, which shall
exclusively govern the relationship between the parties,


                                      -2-

<PAGE>

except for the following paragraphs of the Prior Tenancy Agreement which are
incorporated herein by this reference: (Paragraph Symbol) 2 (Security Deposit);
(Paragraph Symbol) 6 (No Rent if Lease Agreed Upon); and (Paragraph Symbol) 7
(Expenses Paid by Lessee). Lessee's occupancy pursuant to this Lease shall be
deemed to have commenced as of August 30, 1995.

     C. The annual rental for each year of the Term shall be two hundred thirty
thousand six hundred twenty-five dollars ($230,625.00) for the demised premises
($19,218.75 per month).

     D. It is hereby further stipulated and agreed as follows:

               1. The post-Term rental rate shall be one hundred fifty per cent
          of the rate in effect pursuant to the foregoing paragraph I.C for the
          last calendar month prior to the end of the Term, prorated and payable
          monthly in advance for the period of post-Term occupancy.

               2. As of the date of commencement of the Term, Lessee shall pay
          to Lessor one month's rent in the amount of nineteen thousand two
          hundred eighteen dollars and seventy-five cents ($19,218.75), which
          shall be applied to pay the first month's rent.

               3. As of the date of commencement of the Term, Lessee shall
          establish a security deposit in an amount equal to three months' rent
          by funding an escrow account upon the following conditions which are
          acceptable to Lessor and Lessee: Lessor shall establish an interest
          bearing account for the benefit of Lessee. Lessee shall be responsible
          for all fees and costs associated with such account. The actual
          income, if any, earned by the security deposit shall be added to the
          principal of the security deposit and shall be withdrawn by Lessor and
          paid to Lessee annually. In no event shall Lessee charge against the
          security deposit any amount due from Lessee, and Lessee shall have no
          ability to make withdrawals from such account. After the end of the
          Term, if Lessee shall have surrendered the Premises in accordance with
          subparagraph V.A.5 and is not otherwise in default hereunder, the
          security deposit and accrued interest shall be returned to Lessee by
          Lessor. Lessor hereby acknowledges receipt of one of the three months'
          security deposit pursuant to the Prior Tenancy Agreement.


                                      -3-

<PAGE>

               4. Initially, the limits of the liability insurance for purposes
          of paragraph IV.D shall be not less than $1,000,000 in the event of
          injury or death of one person and $3,000,000 in the event of injury or
          death of more than one person in the same accident and $250,000 for
          damage to property.

               5. As used herein, "Lessee's share" shall mean a fraction the
          numerator of which shall be the number of square feet of floor area in
          the Premises and the denominator of which shall be the number of
          square feet of rentable floor area in all buildings within the 94,505
          square foot Parcel and the lot of approximately 125,116 square feet to
          the northwest also owned by Lessor (said lot and the Parcel being
          referred to collectively as the "Project"). Said fraction is 22,500
          over 145,000, or 16.00 per cent.

     E. Except as otherwise specifically provided herein, any notice, payment,
statement, or other communication required or permitted to be given hereunder by
either party to the other shall be sufficiently given if in writing and mailed
in accordance with Article VIII, paragraph 6 duly addressed

               1. if to Lessor, to 97 Adams Street, Newton, Massachusetts 02195,
          with a copy to Loyd M. Starrett, Esquire, 260 Franklin Street, Boston,
          MA 02110, or

               2. if to Lessee, to 330 Nevada Street, Newton, MA 02160 with a
          copy to Victoria L. Karlson, Esquire, Testa, Hurwitz & Thibeault, 125
          High Street, Boston, MA 02110.

Either party at any time may change its address for purposes of this paragraph
by notice given as aforesaid. Any such notice, statement or other communication
on behalf of a corporation, trust or other entity which contains the
representation that the signatory is thereunto duly authorized shall be
conclusively deemed to be an act of said corporation, trust or other entity so
authorized.


                                      -4-

<PAGE>


     F. Lessor agrees that the commission due to Greg Lucas of Lynch, Murphy &
Partners on account of this lease shall be Lessor's responsibility. Lessee and
Lessor warrant and represent to each other, first, that neither Lessee or Lessor
nor anyone acting on their respective behalf had any contact with any broker
other than said Greg Lucas in any way in connection with any proposed lease or
sale of the demised premises, second, that to the best of their respective
knowledge no broker other than said Greg Lucas has any basis for a claim for a
commission on account of the lease or sale of the Premises, and, third, that to
the best of their respective knowledge no broker other than those hereinbefore
named has asserted or intends to assert any such claim. Lessee and Lessor agree
to indemnify the other and hold it harmless from and against any claim for a
commission by any other broker who claims to have shown the demised premises to
Lessee or anyone acting on its behalf.

                                   ARTICLE II

     A. The Premises comprise 22,500 square feet on the second floor of the
Building at 330 Nevada Street in the City of Newton which is situated on a
Parcel of approximately 94,505 square feet of land outlined in red on the site
plan attached hereto and marked "B". The Project contains approximately 219,625
square feet of land, including the Parcel, and is the property conveyed to the
Lessor by deed of TRW Foundation dated September 14, 1984 and recorded in the
Registry as Document 667,835. The Building


                                      -5-

<PAGE>

and the Parcel are subject to and have the benefit of all rights, easements,
restrictions and agreements of record and the easements and restrictions shown
on or referred to on the said site plan and in the schedule attached hereto,
made part hereof and marked "Exhibit C", including but not limited to rights of
way appurtenant to other buildings.

     B. Lessor covenants and agrees with Lessee to cause to be made renovations
of the Building and leasehold improvements of the Premises in accordance with
the schedule of Lessor's work attached hereto, made part thereof, and marked "D"
("Lessor's Work"), except that Lessor may vary Lessor's Work, with prior written
notice to Lessee, to such extent, if any, as (i) local laws, ordinances or
regulations may require, (ii) may be necessary by reason of unforeseen site
conditions or (iii) may be requested by a present or prospective Institutional
Mortgagee if such variance does not adversely affect the usable space, basic
function or structural integrity of the Premises. Said Lessor's Work shall be
without cost to Lessee and shall be substantially completed prior to January 1,
1996, with the exception of Items 1 through 5 of Part I of Exhibit D, which
Items shall be completed by October 31, 1995. All work shall be done in good and
workman like manner and in compliance with all applicable laws and lawful
ordinances, by-laws, regulations and orders of governmental authority and of the
insurers of the Building. All permits necessary for work required of Lessor
pursuant to this paragraph are Lessor's responsibility. Lessor agrees to obtain
a building


                                      -6-
<PAGE>

permit at Lessor's sole cost and expense (should a building permit be required)
to complete Lessor's Work.

     Lessee shall be responsible for filing and prosecuting applications for all
licenses, permits or other approvals required by reason of tenant improvements
or because of the nature of Lessee's business, and Lessor shall cooperate with
Lessee as needed to obtain all such licenses, permits or other approvals. The
issuance of such licenses, permits or approvals shall not be a condition
precedent to the commencement of the Term.

     C. Lessor shall commence the work required of Lessor by the foregoing
paragraph B with reasonable dispatch after all permits, licenses and approvals
necessary for such work have been obtained from the appropriate governmental
authorities, and, except for delays due to government regulation, inability to
obtain labor or materials, unusual weather conditions, action or failure to act
by Lessee, or other causes beyond Lessor's reasonable control, shall prosecute
the same with diligence. If, other than due to circumstances beyond Lessor's
reasonable control mentioned in the foregoing sentence, Lessor fails to complete
Lessor's Work to the Premises by January 15, 1996, Lessor shall pay to Lessee
liquidated damages equal to $100 per day between January 15, 1996 and the
substantial completion of Lessor's Work. Lessor warrants that Lessor's Work
shall be free from defects for one (1) year from the date of commencement of the
Term, or one (1) year from the date of substantial completion of Lessor's Work,
whichever is later.


                                       -7-

<PAGE>

     D. Lessor's Work shall be deemed "substantially completed" when (1) a
certificate of occupancy has been issued by the building department of the City
of Newton and (2) all work required of Lessor has been completed except for (a)
items of work which are minor in nature and (b) other items of work, including
mechanical adjustment of equipment and fixtures, which because of the season or
weather or the nature of the items are not practicable to do at the time,
provided that (i) none of the remaining items is necessary to make the Building
tenantable for Lessee's uses, (ii) said items can be completed without material
interference with Lessee's installation of fixtures or doing business and (iii)
Lessor and Lessee have both signed a "punch list" specifying said items. Lessor
shall finish those items referred to in clause (2)(a) of the preceding sentence
within thirty (30) days after substantial completion of Lessor's Work and all
other items as soon as conditions practicably permit, but no longer than sixty
(60) days thereafter.

     E. Lessor covenants promptly to remedy at its sole cost and expense any
structural failure of the Building and any major failure of the plumbing,
electrical, heating, air conditioning, ventilating and other mechanical systems
(or any defect in Lessor's Work for twelve (12) months from the date of
commencement of the Term, or one (1) year from the date of substantial
completion of Lessor's Work, whichever is later) or noncompliance with the
Building or Premises with respect to any applicable laws, statutes, or
ordinances in effect at the date of the commencement of the Term, but otherwise
Lessor shall have no


                                       -8-

<PAGE>

obligation for maintenance or repair of the Premises or for any defect therein.
For purposes of the preceding sentence, if the system in question is a complete
failure, Lessor agrees that it is its responsibility to replace the same. Nor
shall any obligation of Lessor with respect to the Building extend to liability
for the contents of the Premises, which are Lessee's sole responsibility, or for
any consequential damages whatsoever. The word "structural" as used in this
paragraph refers to the foundation, exterior walls, structural columns and beams
and roof of the Building.

     F. During the Lessee's use and occupancy prior to the date of commencement
of the Term, Lessee may make such improvements to the Premises as it shall
desire and install therein fixtures, supplies, and other property in each
instance by prior permission of Lessor. Lessor acknowledges its approval of the
present state of the Premises. However, such use or occupancy of the Premises
shall be upon the following covenants and such other conditions:

               1. Lessee shall not interfere with installation of improvements
          or other work to be done pursuant to the foregoing paragraph B.

               2. While Lessee or any person acting on behalf of or claiming
          under Lessee may be making improvements to the Premises or installing
          in the Premises fixtures, supplies or other property, Lessee and any
          such person shall be in the Premises at their own risk; and Lessee
          agrees to indemnify Lessor and hold him harmless with respect to any
          injury to persons or property (including property rented or leased by
          Lessor and property of Lessor and/or his employees or agents)
          resulting from or arising out of the presence of Lessee or any such
          person on the demised premises pursuant to this paragraph unless such
          injury is due to


                                       -9-

<PAGE>

          the sole negligence of Lessor or its employees, agents or contractors
          or any other person for whom Lessor is responsible.

               3. Lessor shall in no event have any obligation to anyone on
          account of any improvements, fixtures and other property thus
          installed by Lessee as shall become part of the real estate.

                                   ARTICLE III

     A. TO HAVE AND TO HOLD the demised premises unto Lessee, together with all
rights, privileges and appurtenances thereto belonging, for the Term, unless
this lease be sooner terminated as hereinafter provided.

     B. Each party agrees, in order to make a record thereof, upon demand by the
other party at any time or times (whether before, during or after the Term)
forthwith to execute and acknowledge a written declaration in recordable form
setting forth, among other things, (1) the date of commencement of the Term or
(2) the date of termination of this lease. In addition, Lessor shall, if Lessee
so requests, execute and acknowledge such a declaration evidencing any approval
given by Lessor pursuant to paragraph V.A.

     C. If Lessor permits Lessee to continue in actual possession of the demised
premises after the end of the Term, such actual possession shall be deemed not
to extend or renew the Term of this lease. Such actual possession shall be
deemed a tenancy at sufferance if it does not endure more than seven (7)
calendar days; otherwise such actual possession shall be deemed to have


                                      -10-

<PAGE>

created a tenancy at will, from month to month, commencing immediately after the
end of the Term. In either event such tenancy shall be upon the terms herein
contained.

     D. Subject to the rights of existing tenants as of the date of this Lease,
Lessor agrees, throughout the Term of this Lease other than during the last
twelve (12) months hereof, to notify Lessee in writing of all space that becomes
available in the Building. Lessee shall be given fourteen (14) days from
Lessee's receipt of said notice within which to agree to lease any such space,
as is, upon expiration of the prior tenancy, which shall be exercised by written
notice to Lessor, and twenty-one (21) additional days from the date Lessee
receives the initial draft of such expansion lease or expansion amendment to
execute a mutually acceptable lease or amendment to this Lease for such space
(the "Expansion Lease" or "Expansion Amendment"). The rent for any expansion
space shall be no less than provided for herein and may be adjusted to reflect
then prevailing market rates, and any build-out shall be at Lessee's sole
expense. Otherwise, the Expansion Lease or Expansion Amendment shall be on
substantially the same terms and conditions as this Lease. The term of any
Expansion Lease or Expansion Amendment shall be coterminous with the Term of
this Lease.

                                   ARTICLE IV

     A. YIELDING AND PAYING THEREFORE to Lessor, at his then current address
designated pursuant to Article I hereof or at


                                      -11-

<PAGE>

such other place as Lessor may from time to time designate in writing, rent as
follows:

               1. an annual rental for the Term, at the rate specified in
          Article I, payable in equal monthly installments of $19,218.75 in
          advance, the first such monthly installment being due and payable on
          the date of commencement of the Term or the earliest first day of a
          month when the conditions, if any, specified in the certificate of
          occupancy for the Building have been satisfied (whichever is later)
          and subsequent installments being due and payable on each and every
          first day of a month thereafter during the Term;

               2. use and occupancy charges, payable monthly in advance, at the
          post-Term rental rate specified in Article I for any period after the
          Term during which Lessee has actual possession of the demised premises
          or any part thereof;

               3. additional rent in amounts equal to the expense of insurance
          referred to in clause (3) of paragraph IV.E and operating expense for
          maintenance of areas outside the Building used exclusively by Lessee,
          such additional rent being due and payable thirty (30) days after
          Lessor sends an invoice therefor accompanied by a copy of the bill for
          insurance premiums or an itemization of Lessor's operating expenses,
          as the case may be;

               4. any other additional rents herein specifically provided, as
          specified, for example, without limitation in Article V(A)(13);

               5. supplemental rent in an amount equal to the Lessee's share (as
          defined in subparagraph I.D.6 hereof) of the expense of insurance
          referred to in clauses (1) and (2) of paragraph IV.E and operating
          expense for maintenance of common areas of the Project, such
          supplemental rent being due and payable thirty (30) days after Lessor
          sends an itemized statement thereof; and

               6. supplemental rent in an amount equal to Lessee's share (as
          defined in subparagraph I.D.6) of the aggregate of the real estate


                                      -12-
<PAGE>

          taxes assessed to Lessor on the Parcel (including buildings thereon)
          on account of the fiscal year begun July 1, 1995 or any other fiscal
          year during the Term (such taxes being apportioned for the fiscal
          years in which the Term commences and expires) or after the Term while
          Lessee is actually in possession of or occupying the demised premises
          or any part thereof, such amount being due and payable ten days after
          notice to Lessee of the actual tax bill or ten days before the last
          date on which such taxes are payable without interest or penalty,
          whichever is later. Lessor agrees that amounts paid as supplemental
          rent under this subparagraph will be applied to the payment of such
          taxes, and any overpayment will be promptly refunded to Lessee. Lessor
          further agrees if Lessee so requests in writing to furnish to Lessee
          evidence of payment of such taxes. If Lessee requests, in writing/
          Lessor will promptly provide (within fifteen (15) days of receipt of
          said request) copies of statements, bills or invoices for amounts due
          pursuant to the foregoing subparagraphs 1 to 6.

     B. Lessee shall be responsible for Lessee's share (as defined in
subparagraph I.D.5) of all public, special or betterment assessments to the
Premises for improvements installed by the City of Newton during the Term,
except those that benefit only other buildings on the Parcel. Lessor warrants
and represents that as of the date of this lease there are no public, special or
betterment assessments outstanding against the Parcel or the project and that to
the best of his knowledge no such assessment is pending. Lessee shall pay to
Lessor, at least fifteen (15) days before such payment becomes due to the public
authorities, Lessee's share of each installment of any such assessment,
including interest, coming due during the Term or at any other time when Lessee
is actually in possession of or occupying the demised premises, and Lessee shall
pay to Lessor


                                      -13-

<PAGE>

not later than the end of the Term, for any fraction of an installment period at
the end of the Term, the corresponding fraction of the installment, including
interest, for that period. Lessor shall give to Lessee a photocopy of any bill
for such payment at the time such request is made of Lessee, and, if Lessee so
requests in writing, Lessor shall furnish promptly to Lessee appropriate
evidence of each assessment payment. Lessor agrees that all such public, special
or betterment assessments shall be paid over the longest time available without
incurring interest or additional charges.

     C. Lessee may without postponement of payment bring appropriate
proceedings, in the name of Lessor or Lessee or both, for contesting the
validity or amount of the taxes or assessments or to recover payments therefor.
Lessee agrees to save Lessor harmless from all expense in connection with any
such proceeding initiated or controlled by Lessee. Lessor shall cooperate with
Lessee with respect to such proceedings insofar as reasonably necessary. Net
proceeds recovered shall belong to the party who advanced the funds used to make
the payment in question, regardless of who brings such proceedings,

     D. During the Term and at all other times when Lessee has actual possession
of the demised premises or any part thereof, Lessee shall procure and maintain,
at Lessee's cost and expense, comprehensive general liability insurance
(including bodily injury and property damage insurance) protecting Lessor and
Lessee against any claim for personal injury or death of any person or persons
or damage to property arising out of or


                                      -14-

<PAGE>

occurring in connection with the use, occupation and maintenance of the demised
premises or approaches to or exits from the Building or the Parcel, such
insurance to be in amounts not less than the limits specified in subparagraph
I.D.4.

     E. During the Term, Lessor shall. procure and maintain, at Lessee's cost
and expense, (1) insurance providing for payment of replacement costs in event
of damage by fire (including debris removal) in an amount not less than eighty
per cent (80%) of the full insurable value of the Building (including, among
other things, the cost of debris removal but not including partitions and other
tenant's improvements installed by Lessee) as from time to time determined by
agreement or by the appraisal of an accredited insurance appraiser selected by
Lessor and reasonably satisfactory to Lessee; (2) insurance against sprinkler
damage and those hazards customarily referred to as extended coverage and (3)
insurance against abatement or loss of rent in case of fire or other casualty in
an amount at least equal to the annual rental and supplemental and additional
rentals to be paid by Lessee during one year next ensuing. Lessor will provide
certificates of insurance to Lessee upon written request.

     F. Each party, notwithstanding any provisions of this lease to the
contrary, waives any rights of recovery against the other for loss or injury
against which the waiving party is protected by insurance containing provisions
denying to the insurer acquisition of rights by subrogation. All insurance,
whether or not required, carried by either Lessor or Lessee with respect to the
demised premises or occurrences thereon shall include either


                                      -15-

<PAGE>

provisions designating the other party as one of the insured or as a loss payee
or provisions denying to the insurer acquisition by subrogation of rights of
recovery against the other party. If either party is unable, without extra cost,
to obtain insurance coverage which will not be impaired by the foregoing waiver,
such party shall so notify the other party and the notified party shall have the
right to pay such cost or, in the alternative, to place such insurance (for the
notifying party's account and its expense) if by doing so the party placing such
insurance may, without such extra cost, secure insurance coverage which will not
be thus impaired from responsible carriers at rates as favorable as those
otherwise available to the other party.

     G. All required insurance shall be written by responsible companies
reasonably satisfactory to Lessor and in the forms customarily in use from time
to time in the locality.

               1. All such insurance policies shall provide that the same shall
          not be cancelled without at least ten (10) days' prior written notice
          to each insured named therein.

               2. Prior to Lessee's taking actual possession of the Premises and
          from time to time thereafter (in each case prior to the expiration
          dates shown by like documentation previously furnished), Lessee shall
          furnish to Lessor insurance policies, duplicates or certificates of
          insurance demonstrating compliance at all times with subparagraph
          I.D.4 and paragraphs IV.D and F.

               3. If Lessee shall fail to procure and maintain insurance in
          amounts and containing provisions in accordance with subparagraph
          I.D.4 and paragraphs IV.D and F, Lessor may, after written notice to
          Lessee, do so and charge premiums therefor to Lessee as additional
          rent.


                                      -16-

<PAGE>

     H. Lessee shall not acquire as an insured party under any insurance on the
Building other than insurance covering only tenant's improvements or as a payee
of any proceeds of such insurance any right to participate in the adjustment of
any loss or to receive the proceeds. Lessee agrees upon request promptly to
endorse and deliver to Lessor or any Mortgagee specified by Lessor any checks or
other instruments issued on account of such insurance in payment of loss.
Proceeds of insurance covering both the Building and tenant's improvement shall
be fairly apportioned according to the respective losses.

                                    ARTICLE V

     A. Lessee covenants during the Term hereof and at any other time when
Lessee has actual possession of the Premises or any part thereof

               1. to pay when due all charges for water, electricity, telephone,
          gas, sewer, heat and other utility services rendered to the Premises
          and service inspections made therefor, whether called charge, tax,
          assessment, fee or otherwise;

               2. to use the Premises only for purposes set forth in the
          schedule attached hereto and marked Exhibit B and for such other uses
          as may be specifically approved in writing by Lessor; and to procure
          all licenses and permits from time to time required by law in
          connection with such uses, except that Lessor shall obtain the initial
          building permit and certificate of occupancy;

               3. to keep and maintain the demised premises, and those portions
          of the Building used exclusively by Lessee and every part thereof, in
          as good condition and repair as the


                                      -17-

<PAGE>

          same are in at the commencement of the Term or may be put in during
          the continuance thereof, subject to the provisions of paragraph II.F
          and Article VII hereof, the effects of damage by fire and other
          casualty insured against and reasonable wear or tear excepted; and,
          without limiting the generality of the foregoing, to Keep all glass
          whole and in good condition and to replace with glass of the same
          quality any glass which may be broken (except for damage insured
          against), to make all repairs, including interior repainting, as
          needed, and to keep exterior windows and doors and all plumbing,
          sanitary waste disposal, lighting, heating, air conditioning,
          sprinkler and other utility systems serving the Premises in good
          operating condition;

               4. to maintain control over the Premises;

               5. promptly at the expiration of the Term or earlier termination
          of this lease, to remove all goods and effects which are not the
          property of the Lessor, including Lessee's signs, goods, effects,
          furniture, laboratory equipment, personal property and any machinery,
          fixtures and equipment used solely in the conduct of Lessee's
          business, which Lessee may remove upon repairing any damage caused by
          such removal, and peaceably to yield up to the Lessor the Premises and
          all improvements, alterations and additions thereto, and all fixtures
          and equipment servicing the Premises, except such as were installed by
          Lessee and can be unscrewed or unbolted without damage to the Premises
          or with damage completely repaired by Lessee, clean and neat and in as
          good order, repair and condition as the same were in at the
          commencement of the Term or were put in thereafter, the effects of
          damage by fire and other casualty insured against or reasonable wear
          and tear excepted; and, in the event Lessee fails to so yield up the
          Premises in such order, repair and condition, to reimburse Lessor for
          all expenses, including reasonable attorneys' fees, incurred in
          obtaining possession of the Premises and putting the Premises in such
          order, repair and condition; for purposes of this paragraph, "the
          property of the Lessor" includes, without limitation, existing lab
          benches, fume hoods, and four (4) walk-in refrigerator chests;


                                      -18-

<PAGE>

               6. to hold Lessor harmless and indemnified from any liability for
          injury, loss, accident or damage to any person or property which
          arises out of or in connection with Lessee's use or occupancy of the
          Premises or tenancy in the Parcel, unless such liability arises out of
          or results from the negligence or willful misconduct of Lessor or his
          agents or employees or persons acting under contract with him, and
          from any claims, actions, proceedings, or cost (including reasonable
          counsel fees) in connection therewith, including injury to or death of
          persons and damage to property while in the Building or on the
          Premises and injury to or death of, or damage to property of, persons
          who are patrons, customers, invitees, employees or servants of Lessee
          while in or on private ways or parking areas within the Project and
          which arises out of or results from the negligence of Lessee, its
          agents, employees or contractors, but excluding injury or damage
          arising out of or resulting from the negligence or willful misconduct
          of Lessor or his agents, employees or contractors; and to keep all
          Lessee's employees working in the Premises covered by workmen's
          compensation insurance and require contractors working in the Premises
          to keep all employees similarly insured, furnishing Lessor with
          certificates thereof;

               7. not to take or permit to be taken any action, or omit to take
          any action, which will result in the suspension, forfeiture or
          cancellation of any license or permit with respect to the Premises of
          which Lessee knows;

               8. not, without on each occasion first obtaining Lessor's
          approval, which will not be unreasonably withheld or delayed, endorsed
          upon the plans therefor, to erect any building, fence, wall, exterior
          lighting or other structure, nor to make any exterior alteration or
          addition, nor to make any interior alteration or addition except
          installation of fixtures and equipment which do not damage the
          Building in any material respect;

               9. not to permit any condition or use of the Premises or action
          thereon which is objectionable by reason of noise, odor, vibration,
          smoke, radiation, or the hazardous nature of the use, nor to permit
          any auction sale thereon; provided, however, that the ordinary


                                      -19-

<PAGE>

          commercial operations of any business expressly permitted by the
          schedule attached hereto and marked Exhibit B shall in no event be
          deemed to violate this clause;

               10. not to solicit trade by sound audible outside the Premises,
          nor to permit on the Premises any nuisance, nor to permit any use of
          the Premises which may be offensive to other occupants of the Project
          or contrary to law or ordinance or by-law, regulation or order of
          public authority or which may invalidate any insurance on the Building
          or its contents or render necessary any alteration or addition to the
          Building;

               11. not to injure, overload or deface the Building or any part
          thereof, nor to make or suffer any waste of the Premises;

               12. not to assign this lease or sublet the Premises or any
          portion thereof without first obtaining on each occasion Lessor's
          written consent, which will not be unreasonably withheld, conditioned
          or delayed, provided, however, (a) that Lessee may, without such
          consent, but after notice to Lessor of the name and address of the
          assignee, assign this lease or sublet all or any part of the Premises
          to any firm or corporation which controls or is owned or controlled by
          Lessee or under common control with Lessee, (b) that no assignment or
          subletting shall relieve Lessee of any obligation or liability
          hereunder and (c) that, unless and until Lessor specifically consents
          thereto in writing (which further consent shall not be unreasonably
          withheld, delayed or conditioned), (i) no assignee or sublessee shall
          further assign this lease or sublet any part of the Premises and (ii)
          the ownership or control of a firm or corporation which receives a
          sublease pursuant to the foregoing clause (a) shall not thereafter be
          changed; and provided further that, in the case of assignment or
          sub-letting of the Premises, Lessor may reasonably condition his
          consent on Lessee's agreeing to pay as additional rent the excess of
          the amount received by Lessee as a result of such subletting or
          assignment over the sum of the annual additional and supplemental rent
          required hereunder less only the following Lessee's costs and
          expenses, if actually incurred by Lessee, in connection with such
          sublet or


                                      -20-

<PAGE>

          assignment: broker's commissions, reasonable attorney's fees and any
          renovation or other work done to the Premises.

               13. to permit Lessor, utility companies and any person properly
          identified to Lessee as having an interest under any mortgage
          affecting the Building to have free access to the Premises (including
          the right to take upon or through, or to keep and store within, the
          Premises all necessary materials, tools and equipment, minimizing, for
          all purposes to the extent possible the time and space which such
          materials, tools, and equipment would be kept or stored within) in any
          case of emergency and otherwise during normal business hours and upon
          reasonable notice to Lessee for the purposes of inspection or of
          making repairs, alterations or renovations or of maintaining any part
          of the demised premises or of complying with laws, orders and
          requirements of governmental or other lawful authority or of
          fulfilling the obligations of this lease or of exercising any other
          right reserved to Lessor by this lease; any access permitted hereunder
          shall be subject to the following terms and conditions: that such
          access (i) does not unreasonably interfere with, interrupt, or damage
          Lessee's business, the Demised Premises, or Lessee's use and enjoyment
          thereof or access thereto or egress therefrom; (ii) does not decrease
          the square footage or volume of the Demised Premises; (iii) with
          respect to the relocation or alteration of any pipes, ducts, conduits,
          wires and appurtenant fixtures, or the like, the same shall be located
          to the extent possible, in Lessor's discretion, in the central core of
          the Building, above ceiling surfaces, below floor surfaces or within
          perimeter walls of the Demised Premises; (iv) to the extent possible,
          Lessor shall perform any such maintenance and repairs at times other
          than Lessee's normal business hours; (v) Lessor shall complete such
          maintenance and repairs with reasonable due diligence; and (vi) Lessor
          shall completely restore and clean any areas of the Demised Premises
          affected by such maintenance and repairs.

               14. to permit Lessor, at reasonable times and upon notice to
          Lessee 24 hours in advance, to enter to view the Premises, or to show
          the Premises to any person considering buying the


                                      -21-

<PAGE>

          demised premises (whether before or after the execution of a contract)
          or, at any time within twelve months next preceding the expiration of
          the Term, to any person considering leasing the Premises; and, at any
          time within six months next preceding the expiration of the Term, to
          permit notices for letting or selling to be affixed to an appropriate
          part of the Premises (other than windows and doors) and remain thereon
          without hindrance or molestation;

               15. to comply with such reasonable Rules and Regulations
          consistent with this lease as Lessor hereafter may make for the care
          and use of the Parcel, the Building, its surroundings and facilities
          which it may communicate in writing to Lessee, and which it agrees to
          enforce uniformly with regard to all tenants at the Project, although
          it is agreed that Lessor shall have no obligation to enforce such
          Rules and Regulations or the terms of any lease as against any tenant;

               16. to keep all property of any kind belonging to the Lessee or
          any person claiming through it that may be on the Premises at the sole
          risk of the Lessee; and if the whole or any part thereof shall be
          destroyed or damaged by fire, water or otherwise, or by use or abuse
          of water, or by the leaking or bursting of water pipes or sprinklers,
          or in any other way or manner, no part of said loss or damage is to be
          charged to or borne by the Lessor in any case whatever except to the
          extent that the same is a direct result of negligence or willful
          misconduct of Lessor or his agents or employees or persons acting
          under contract with him or of failure of Lessor to perform his
          obligations hereunder after notice and the lapse of the period of time
          applicable pursuant to paragraph C of Article VI; and

               17. to permit Lessor to remove and store in any public warehouse
          or elsewhere at Lessee's risk and expense and in the name of Lessee
          any or all property not removed from the Premises within 5 days of the
          termination of this lease; and, if Lessee shall then be in default
          under the provisions hereof, Lessor may immediately or at any time
          thereafter upon at least twenty (20) days written notice to Lessee
          sell at public or private sale any or all of such property (regardless
          of whether or not so


                                      -22-

<PAGE>

          removed by Lessor) and apply the net proceeds of such sale to the
          payment of any sum or sums due hereunder; and Lessor shall not be
          liable therefor to Lessee or to any other person in any manner, except
          that Lessee shall be entitled to any balance of such net proceeds
          after payment of all sums due hereunder.

     B. All repairs, alterations, improvements, additions, and restoration by
Lessee or Lessor hereafter required or permitted shall be done in good and
workmanlike manner and in compliance with all applicable laws and lawful
ordinances, by-laws, rules, regulations and orders of governmental authorities
having jurisdiction, of any Board of Fire Underwriters (or other body hereafter
constituted and exercising similar functions) and governing insurance ratings
bureaus, and of the insurers of the Building. All improvements, alterations and
additions to the Building and fixtures and equipment appurtenant to it made or
installed at any time by either Lessor or Lessee shall be part of the Building,
but not signs, machinery, fixtures or equipment installed by Lessee which can be
unscrewed or unbolted without damage to the Premises or with damage completely
repaired by Lessee, nor any items which Lessor has agreed prior to installation
shall be removable by Lessee. Each party doing any construction or other work
agrees to pay for it and discharge promptly any liens arising therefrom (or
provide a lien bond resulting in such discharge).

     C. This lease shall be subordinate to any Mortgage of the Parcel and/or the
Building securing a note or bond issued by or at the request of Lessor if either
(i) the Mortgagee agrees to recognize this lease in the event of foreclosure,
deed in lieu of


                                      -23-

<PAGE>

foreclosure or taking of possession (unless the Term has then expired or Lessor
then has the right to terminate this lease by reason of Lessee's default) and to
perform all of Lessor's obligations hereunder in the event of such foreclosure
of the mortgage, deed in lieu of foreclosure and the taking of possession of the
Premises by the Mortgagee or (ii) such Mortgage contains apt provisions under
the terms of which the existence of this lease shall be recognized and so long
as Lessee and its successors and assigns shall keep and perform the terms,
covenants and conditions in this lease contained on its part to be kept and
performed, neither any Mortgagee nor any holder or owner of the indebtedness
secured thereby, nor any other person, shall, in attempting to force collection
of said indebtedness or to realize upon such security, have any power to impair,
modify, abrogate, or adversely affect the rights of Lessee under this lease, to
the full enjoyment of the entire Term, to the end that Lessee, while not in
default beyond applicable cure periods hereunder, shall notwithstanding the
creation of or default under any such mortgage or indebtedness secured thereby,
peacefully and quietly have, hold and enjoy the Premises for the entire Term and
all other rights, privileges and benefits to which it may be entitled under and
pursuant to the terms of this lease. Lessor shall make all reasonable efforts to
obtain a Non-Disturbance from the Lessor's mortgagees in recordable form within
sixty (60) days from the date of this Lease. Lessee agrees upon request of
Lessor or any Mortgagee to execute and deliver all such instruments as may be
appropriate to evidence such subordination of this lease.


                                      -24-
<PAGE>

Upon receipt of notice of entry to foreclose any Mortgage of the demised
premises Lessee may recognize such Mortgagee and anyone claiming under such
Mortgage, including the purchaser at foreclosure sale, as successor to Lessor's
interest and rights hereunder and, if requested, shall attorn to such Mortgagee
or purchaser. However, in no event shall any Mortgagee be responsible for
breaches hereunder occurring other than during its period of ownership after
such foreclosure and taking of possession as aforesaid. Any Mortgagee may
subordinate its Mortgage to this lease, without Lessee's consent, by notice in
writing to Lessee, and thereupon this lease shall be deemed to be prior in lien
to such Mortgage (without regard to their respective dates of execution and
delivery) and to have been assigned by Lessor to such Mortgagee.

     D. Lessor covenants and agrees that Lessee, on paying the annual rent,
additional rent and supplemental rent and performing the Lessee obligations of
this lease and subject to the terms hereof, shall peacefully and quietly have
and hold and enjoy the Premises through the Term or until this lease is
terminated as herein provided.

     E. Lessor further covenants and agrees at Lessee's expense (as provided in
paragraphs IV.A.3 and 5 hereof) to maintain the exterior of the Building (except
for replacement of glass) and keep in repair all common areas of the Parcel, all
drainage systems, sidewalks and steps. As part of such maintenance, Lessor will
keep the parking areas and driveways on the Parcel and the Project suitably
paved and marked for parking and traffic


                                      -25-

<PAGE>

flow and reasonably free of snow, ice, refuse, and obstructions. Lessor shall
also keep reasonably free of snow, ice and refuse and free of obstructions to
the extent required by the business operations of the tenants of the Building
all sidewalks, steps and other areas used for passage by Lessee exclusively or
in common with others.

                                   ARTICLE VI

     A. This lease is upon the further condition that, if Lessee shall neglect
or fail to perform or observe any of Lessee's covenants herein or any other
written obligation of Lessee to Lessor relating to this lease and referring to
this paragraph and such neglect or failure shall continue (and, in the case of
nonmonetary obligations, Lessee shall not have commenced and diligently
prosecuted the curing of such neglect or failure) after written notice is given
to Lessee, for a period of ten (10) days in case of nonpayment of money, or
otherwise thirty (30) days, or if Lessee shall be dispossessed therefrom by or
under any authority other than Lessor, or if the leasehold hereby created shall
be taken on execution or by other process of law, or if any assignment or trust
mortgage shall be made of Lessee's property for the benefit of creditors, or if
a receiver or similar officer shall be appointed to take charge of all or any
part of Lessee's property by a court of competent jurisdiction and shall not be
discharged within sixty (60) days after his appointment or if Lessee commits any
act of bankruptcy or is


                                      -26-

<PAGE>

adjudged bankrupt, or if a petition is filed by Lessee under any insolvency of
bankruptcy law, or if a petition is filed against- Lessee under any insolvency
or bankruptcy law, and the same shall not be dismissed within sixty (60) days
after the date upon which it is filed, then, and in any of said cases, Lessor
lawfully may, in accordance with applicable law, immediately or at any time
thereafter and without demand or notice, enter upon the Premises or any part
thereof in the name of the whole and repossess the same as of Lessor's former
estate and expel Lessee and those claiming through or under it and remove its
and their effects, forcibly if necessary, without being deemed guilty of any
manner of trespass and without prejudice to any remedies which might otherwise
be used for arrears of rent or preceding breach of. covenant, and upon such
entry this lease shall terminate. Lessee covenants that, in case of such
termination or in case of termination under the provisions of statute by reason
of the default of Lessee, Lessee will at the election of Lessor (which election
may be made at any time) either

               1. pay to Lessor, on account of the unexpired portion of the
          Term, sums equal to the rent and other payments herein required at the
          same times and in the same installments as such payments would be due
          hereunder, provided that (a) Lessor shall be using or shall have used
          reasonable efforts to relet the Premises and (b), if the demised
          premises or any portion thereof shall have been relet, the sums so
          payable by Lessee shall be abated in an amount equal to the excess of
          moneys actually received from the new tenant over Lessor's reasonable
          expenses of such reletting, including, without limiting the generality
          of the foregoing, the cost of remodeling and attorneys' and realtors'
          fees, or


                                      -27-

<PAGE>

               2. pay to Lessor, as liquidated damages, a sum which at the time
          of such termination represents the amount, if any, by which the then
          fair market rental value of the Premises is less than the rent and
          other payments herein required for the residue of the Term, or

               3. indemnify Lessor against loss of the rent and other payments
          herein required from the time of such termination during the residue
          of the Term, provided that (a) Lessor shall be using or shall have
          used reasonable efforts to relet the Premises and (b), if the demised
          premises or any portion thereof shall have been relet, the sums so
          payable by Lessee shall be abated in an amount equal to the excess of
          moneys actually received from the new tenant over Lessor's reasonable
          expenses of such reletting, including, without limiting the generality
          of the foregoing, the cost of remodeling and attorneys' and realtors'
          fees.

Nothing herein contained shall, however, limit or prejudice the right of Lessor
to prove for and obtain in proceedings for bankruptcy or insolvency by reason of
the termination, an amount equal to the maximum allowed by any statute or rule
of law in effect at the time when, and governing the proceedings in which, the
damages are to be proved, whether or not the amount be greater, equal to, or
less than the amount of the loss or damage referred to above.

     B. If Lessee shall default in the performance or observance of any
agreement, condition or other provision in this lease contained on its part to
be performed or observed and shall not cure such default within thirty (30) days
after notice in writing has been given from the Lessor specifying the default
(or shall not within said period commence to cure such default and thereafter
prosecute the curing of such default to completion with due diligence), Lessor
may, at its option at any time thereafter cure


                                      -28-

<PAGE>

such default at the expense of Lessee. However, if it is necessary to protect
the real estate or Lessor's interest therein or to prevent injury or damage to
persons or property that certain action be taken in less than thirty (30)
days, the notice shall so specify, and Lessor shall have the right to cure such
default on behalf of Lessee if no action is initiated by Lessee prior to the
time specified in the notice. Lessor's cure of such default shall not be deemed
to waive any claim for breach of this lease, but thereafter Lessee's cure shall
be by the payment required by the following sentence. If by reason of any breach
Lessor is compelled or elects to pay any sum of money or to do any act which
will require the payment of any sum of money or to incur any expense, including
reasonable attorneys' fees, in instituting or prosecuting any proceeding to
enforce Lessor's rights hereunder, the sum or sums so paid or paid on account of
such expense shall be deemed to be due from Lessee to Lessor forthwith following
the payment thereof by Lessor except in the case of a legal proceeding and, in
that case, upon the entry of final judgment in favor of Lessor; interest thereon
shall accrue at the rate of two per cent (2%) per month from the date due.

     C. If Lessor shall fail to perform any obligation hereunder and shall not
cure such failure within thirty (30) days after notice in writing from the
Lessee specifying the failure (or shall not within said period commence to cure
such failure and thereafter prosecute the curing of such failure to completion
with due diligence), Lessee may thereafter cure such failure at the expense of
Lessor. If it should be necessary to protect the


                                      -29-

<PAGE>

real estate or Lessee's interest therein or to prevent injury or damage to
persons or property that certain action be taken in less than thirty (30) days,
the notice (which shall be written unless it is an emergency, in which case
notice may be oral if followed by written notice within one (1) day) shall so
specify, and Lessee shall have the right to cure such failure on behalf of
Lessor if no action is initiated by Lessor prior to the time such action must be
taken or the time specified in the notice, which-ever is later. If to cure any
such failure Lessee is compelled to pay any sum of money or do any act which
will require the payment of any sum of money or to incur any expense, including
reasonable attorneys' fees, in instituting or prosecuting any proceeding to
enforce Lessee's rights hereunder, the sum or sums so paid or paid on account of
such expense shall be deemed to be due from Lessor to Lessee within fifteen (15)
days of Lessor's receipt of a written request for said reimbursement which
notice shall include supporting documentation of such costs or expenses actually
incurred and paid following the payment thereof by Lessee except in the case of
a legal proceeding and, in that case, upon the entry of final judgment in favor
of Lessee; interest thereon shall accrue at the rate of two per cent (2%) per
month from the date due. However, no such sum nor any other monetary claim shall
in any event be deducted from or set off against any installment otherwise
payable by Lessee on account of annual or supplemental rental.

     D. After receiving written notice from an Institutional Mortgagee that it
holds a mortgage upon all or any part of the


                                      -30-
<PAGE>

demised premises no default notice from Lessee to Lessor shall be effective as
against said Mortgagee, so long as such mortgage is outstanding, unless and
until a copy of the same is mailed to such Mortgagee, and the curing of any
failure by such Mortgagee within a reasonable time shall be deemed to be a
performance by Lessor. Accordingly, no act or failure to act on the part of
Lessor which would entitle Lessee under the Terms of this lease, or by law, to
be relieved of Lessee's obligations hereunder or to terminate this lease shall
result in a relief of such obligations or a termination of this lease unless (1)
Lessee shall have first given written notice of Lessor's act or failure to act
to the Institutional Mortgagee, if any, specifying the act or failure to act on
the part of Lessor which could or would give basis to Lessee's rights and (2)
such Mortgagee, after receipt of such notice, has failed or refused to correct
or cure the condition complained of within a reasonable time thereafter. A
"reasonable time" for purposes of this paragraph shall be determined by
reference to the time this lease allows for Lessor to cure in the same
circumstances. It is understood, however, that nothing contained in this
paragraph shall be deemed to impose any obligation on any Mortgagee to correct
or cure any failure.

                                   ARTICLE VII

     A. In the event of damage to or destruction of the Building or the Premises
during the Term by fire or other casualty (or by the action of any public
authority in connection therewith) to a


                                      -31-

<PAGE>

value exceeding the applicable percentage (according to the following table) of
the sound insurable value thereof for fire insurance purposes (as determined in
connection with the actual insurance adjustment), this lease may be terminated
at the election of Lessor or Lessee.

<TABLE>
<CAPTION>
Years of Term then remaining   applicable percentage
----------------------------   ---------------------
<S>                            <C>
less than 5                             25%
</TABLE>

               1. If Lessor may not or does not elect to terminate and Lessee
          may not or does not elect to terminate, this lease shall continue in
          force and the Lessor shall use due diligence to repair or restore the
          Premises to their condition prior to such fire or casualty, to the
          extent permitted by the net proceeds of insurance recovered for such
          destruction or damage and by zoning and building laws then applicable.
          If the net proceeds are insufficient for full restoration, Lessee may,
          at its election, advance additional funds sufficient to allow full
          restoration, and in that event Lessor shall cause the Premises to be
          restored as fully as the applicable laws permit.

               2. Notwithstanding anything to the contrary in this Article, if
          Lessor fails to complete such repair or restoration as is required by
          the foregoing subparagraph 1 in one hundred eighty (180) days. Lessee
          may then elect to terminate this lease.

     B. In the event that during the Term the whole of the demised premises
shall be taken for public purposes by any public or quasi-public authority
having jurisdiction, this lease shall terminate automatically. This lease may be
terminated at the election of either Lessor or Lessee if (i) a taking for public
purposes by any public or quasi-public authority having jurisdiction, impairs
Lessee's access to the Parcel or the


                                      -32-

<PAGE>

Premises or (ii), as a result of a taking of a portion of the Building, (a) the
remainder of the Premises is not reasonably suitable for Lessee's continued use
or (b) the reasonable cost to put the remainder of the demised premises in
reasonable condition for use by Lessee is in excess of $25,000. Lessee, at its
election, may nevertheless continue to use and occupy the Premises, and enjoy
and exercise all of its rights and privileges under this lease, for the period
between the taking and the date on which the authority which made the taking
shall take actual possession of the property taken. During such period of
occupancy, Lessee shall pay use and occupancy charges for the Premises at the
rate of the annual rental which would otherwise be due, and all other
obligations of Lessor and Lessee set forth in this lease shall continue in
effect as if this lease had not been terminated.

               1. Unless so terminated as provided above, this lease shall
          continue in force, and Lessor shall use due diligence to put the
          demised premises, or what may remain thereof, in their condition prior
          to such taking to the extent permitted by net proceeds of damages
          awarded for such taking and by zoning and building laws then
          applicable. If the net proceeds are insufficient to put the demised
          premises in such reasonable condition, Lessee may, at its election,
          provide additional funds sufficient therefor, in which event Lessor
          shall cause the Premises to be restored as fully as the amount of the
          Premises remaining and the applicable laws permit.

               2. Irrespective of the form in which recovery may be had by law,
          all rights to damages or compensation (other than for moving expenses)
          shall belong to Lessor. Lessee hereby grants and assigns to Lessor all
          of


                                      -33-

<PAGE>

          Lessee's rights to such damages and covenants to deliver such further
          assignments thereof as Lessor may from time to time request.

               3. In the event that tenant's fixtures or improvements installed
          by Lessee comprise a portion of the property so taken, there shall be
          paid over to Lessee a portion of the net proceeds of damages awarded
          equal to the same proportion of the net proceeds of damages awarded as
          the aggregate value of the tenant's fixtures and improvements
          installed by Lessee taken is of all property (including land) taken.
          The final decision of any court of competent jurisdiction shall be
          conclusive evidence of any facts found by such court even if Lessee is
          not a party to the action in which the findings of fact are made.

     C. Any election to terminate pursuant to this Article VII shall be made by
the giving of written notice by the party electing to terminate to the other
party within thirty (30) days after the party electing to terminate first
receives actual notice of the facts which give rise to its right to terminate.
However, any termination of the lease pursuant to this Article VII shall be
effective as of the date of the casualty or taking upon which the termination is
based.

     D. In case of restoration of the Premises pursuant to either paragraph A or
paragraph B of this Article VII, unless such restoration is necessitated by
damage or destruction of the Building due to the willful misconduct of Lessee or
Lessee's employees or agents, there shall be an equitable abatement and/or
adjustment of the annual rental on account of any curtailment of Lessee's use of
the Premises. However, whenever Lessee has undertaken to repair or restore the
demised premises, no such


                                      -34-

<PAGE>

temporary abatement of rental shall continue beyond the time when such repairs
or restoration would have been completed if they had been undertaken immediately
and prosecuted diligently.

                                  ARTICLE VIII

     A. The following words and phrases when used in this lease have the
following meanings unless a different meaning is required by the context:

               1. The masculine or neuter gender shall include the masculine,
          feminine and neuter, and the singular shall include the plural.

               2. Whenever this lease expressly requires "approval" or "consent"
          or that something be "approved" by a party, such approval or consent
          and the request therefor shall be in writing, except that when any
          plans, working drawings or specifications or revisions or amendments
          thereof are submitted by one party to the other for its approval the
          same shall be conclusively deemed to have been approved unless within
          fifteen (15) calendar days after such plans, working drawings or
          specifications are mailed the recipient notifies the party seeking
          approval or consent that the recipient does not approve them and
          thereafter, if requested, promptly states its reasons therefor. Nor
          shall any approval or consent expressly required by this lease be
          unreasonably withheld or delayed.

               3. The "date of this lease" is the date inserted on the first
          page hereof. The "date of commencement of the Term" and the "Term" are
          defined in Article I.

               4. The words "herein", "hereof", and "hereunder" refer to this
          instrument as a whole and not merely to the subdivisions thereof in
          which such words appear.

               5. The word "individual" refers only to natural persons, but the
          word "person" refers


                                      -35-

<PAGE>

          to firms, partnerships, trusts, other associations and corporations as
          well as to natural persons. The "family" of an individual includes
          only his brothers and sisters (whether by the whole or half blood) and
          their lineal descendants and the individual's spouse, ancestors, and
          lineal descendants. An "affiliate" of any individual means a member of
          his family or a corporation or other entity controlled, directly or
          indirectly, by that individual. For purposes of the foregoing
          sentence, first, stock owned, directly or indirectly, by or for a
          corporation, partnership, estate, or trust shall be considered as
          being owned proportionately by its shareholders, partners, or
          beneficiaries and, second, an individual shall be considered as owning
          the stock owned, directly or indirectly, by or for his family or by or
          for his partner.

               6. Anything required by this lease to be "mailed" and all
          notices, demands, requests and other instruments which may or are
          required to be given by any party to the other under this Lease shall
          be in writing and shall be deemed to have been properly given two days
          after being sent by United States certified mail, return receipt
          requested, postage prepaid, or when received from an overnight
          delivery service that provides tracking and proof of receipt or by
          hand with proof of receipt. The customary United states Postal Service
          return receipt shall be conclusive evidence of delivery and Post
          Office records shall be conclusive evidence of refusal of delivery.

               7. "Mortgage" shall mean any instrument or group of instruments
          granting a security interest, regardless of what the security
          agreement is called, including but not limited to a deed of trust or
          industrial development financing. "Mortgagee" shall mean any person or
          group of persons who at the time in question holds a Mortgage of any
          part of the demised premises, regardless of whether the person is
          acting as a fiduciary. An "Institutional Mortgagee" is a Mortgagee
          which is a bonding authority, insurance company or accredited lending
          institution. The Massachusetts Industrial Finance Authority shall be
          deemed to be an Institutional Mortgagee.


                                      -36-
<PAGE>

               8. The term "operating expenses" means all such expenses incurred
          by Lessor directly or indirectly in connection with the Project,
          including but not limited to costs of outside maintenance and repairs,
          snow plowing and removal, mowing and landscape maintenance and
          overhead attributable thereto, and excludes the following:

                    (a) payments of principal, interest and any other amounts
          related to mortgages or any other indebtedness;

                    (b) brokerage commissions;

                    (c) wages, salaries or other compensation paid to any
          executive employees of Lessor above the grade of Building Manager;

                    (d) the cost of work done by Lessor for a particular Lessee
          (including, without limitation, architectural, legal or engineering
          costs relating thereto);

                    (e) the initial cost of tools and equipment used in
          operation, management, repair or maintenance of the Project;

                    (f) depreciation;

                    (g) costs for which the Lessor, by the terms of this Lease
          or any other lease or agreement, makes a separate charge;

                    (h) real estate taxes or any payments or charges in lieu
          thereof;

                    (i) capital expenditures which, under generally accepted
          accounting principles as consistently applied in the real estate
          industry for buildings of the type of the Building, are properly
          classified as capital expenditures;

                    (j) ground rent;

                    (k) reserves;

                    (l) costs of repair or other work necessitated by fire or
          other casualty or by the exercise of eminent domain to the extent such
          costs are covered by warranties or Lessor's insurance;


                                      -37-

<PAGE>

                    (m) attorneys' and other professional fees, costs and
          disbursements and other expenses incurred in connection with
          negotiations or disputes with existing or prospective Lessees or other
          occupants of the Project and unrelated to the operation, maintenance
          or management of the Project;

                    (n) amounts paid to subsidiaries or affiliates of Lessor for
          services rendered to the Project, to the extent such amounts exceed
          the competitive costs of such services were they not rendered by such
          subsidiaries or affiliates;

                    (o) any fines or penalties incurred on account of violations
          by Lessor of any governmental rule or requirement, or costs incurred
          as the result of Lessor's negligence;

                    (p) title insurance, automobile insurance, key man and other
          life insurance, long-term disability insurance and health, accident
          and sickness insurance, except only group plans providing reasonable
          benefits to persons of the grade of Building Manager and below to the
          extent employed and engaged substantially in operating and managing
          the Project;

                    (q) any expenditures for which Lessor is reimbursed by third
          parties (other than by Lessees pursuant to provisions comparable
          hereto);

                    (r) management fees (whether or not paid to subsidiaries or
          affiliates of Lessor) to the extent in excess of competitive rates.

               9. The term "net proceeds" means the gross amount of value
          received (whether in money or by credit against indebtedness or
          otherwise and including "pro tanto" payments and other payments on
          account and amounts attributed to interest or costs) less expenses
          reasonably incurred by Lessor in connection with collection of the
          same, including, without limiting the generality of the foregoing,
          fees and expenses for legal and appraisal fees.

               10. The phrase "real estate taxes" (particularly for purposes of
          clause IV.A.6) shall be deemed, so far as practicable, to


                                      -38-

<PAGE>

          include personal property taxes assessed to Lessor on personal
          property which is owned, held or used by Lessee or is part of the
          demised premises and also to include any tax or excise on rents which
          is levied upon or assessed to Lessor as a substitute in whole or in
          part for, or in addition to, real estate taxes assessed on land and
          buildings, or either, and not as a part of a general income tax.
          However, "real estate taxes" shall not include inheritance, estate,
          succession, transfer or other income taxes.

     B. Lessor and Lessee shall on ten (10) days' written request certify as to
the status of this lease to any Mortgagee or a prospective Mortgagee or
purchaser of the demised premises: namely, whether said lease is in full force
and effect, the date to which rent and other charges have been paid, and
whether, to the best of the knowledge of the party so certifying, the Lessor and
Lessee have fully complied with the terms and provisions thereof and, if there
is a claim of noncompliance, the respect in which such noncompliance is claimed.
If in connection with obtaining financing on the demised premises an
Institutional Mortgagee shall request as a condition to such financing
reasonable modifications in the terms and conditions of this lease, or the
execution of additional instruments or documents, Lessee shall not unreasonably
withhold, delay or condition its consent thereto and execution thereof, provided
that such modifications or documents do not increase the monetary obligations of
Lessee hereunder or otherwise adversely affect the monetary or other obligations
or liabilities of Lessee, alter the duration of the leasehold interest hereby
created, or adversely affect the size or use of the demised premises.


                                      -39-

<PAGE>

     C. Except where the context does not permit, each of the terms and
conditions hereof shall also apply to any period of time after the Term during
which Lessee is actually in possession of or occupying the demised premises or
any part thereof.

     D. The obligations of this lease shall run with the land, and this lease
shall be binding upon and enure to the benefit of the respective heirs, devises,
legal representatives, successors and assigns of the parties hereto. However,
the named Lessor shall be liable only for obligations accruing while he is the
owner of the demised premises, provided that such successor expressly assumes
all obligations of Lessor hereunder. When the Lessor (or any successor or assign
of the Lessor) is acting under a trust, the obligations of Lessor shall be
binding upon the trust estate, but not upon any trustee or beneficiary of the
trust individually.

     E. Failure on the part of either Lessor or Lessee to complain of any action
or omission on the part of the other, no matter how long the same may continue,
shall never be deemed to be a waiver by Lessor or Lessee of any of its rights
hereunder. Nor shall any waiver (express or implied) at any time of any of the
provisions hereof by Lessor or Lessee be construed as a waiver of any of the
other provisions hereunder, and a waiver at any time of any of the provisions
hereof shall not be construed as a waiver at any subsequent time of the same
provisions. The consent or approval by Lessor to or of assignment or subletting
or any other action by Lessee requiring the Lessor's consent or approval shall
not be deemed to waive or render unnecessary


                                      -40-

<PAGE>

Lessor's consent or approval to or of any other assignment or subletting or to
or of any subsequent similar act by Lessee; nor shall Lessee's consent or
approval to or of any action by Lessor be deemed to waive or render unnecessary
any required consent or approval to or of any subsequent action.

     F. If any term or provision of this lease or the application thereof to any
person or circumstance shall to any extent be invalid or unenforceable, the
remainder of this lease or the application of such term or provision to persons
or circumstances other than those as to which it is held invalid or
unenforceable shall not be affected thereby, and each term and provision of this
lease shall be valid and be enforced to the fullest extent permitted by law. It
is hereby declared as the intention of the parties hereto that they would have
executed such remainder of this lease and would have provided for such
application to other persons and circumstances without including therein the
term or provision or application thereof hereafter declared invalid or
unenforceable.

     G. This lease is to be construed as a Massachusetts contract, sets forth
the entire agreement between the parties, and may be cancelled, modified or
amended only by a written instrument executed by both Lessor and Lessee.

     H. Any and all controversies or claims in connection with and/or arising
out of this lease shall be settled by arbitration in the City of Boston in The
Commonwealth of Massachusetts in accordance with the commercial arbitration
rules of the American Arbitration Association. Each party shall bear the portion
of


                                      -41-

<PAGE>

the expenses of such arbitration directed in the award resulting therefrom or,
absent any such provision in the award, such expenses shall be borne by the
party or parties against whom such award is made. This paragraph shall be
specifically enforceable and judgment upon the award rendered may be entered in
any court, state or federal, having jurisdiction of the parties. The decision of
the arbitrators shall be a condition precedent to any legal action.


                                      -42-

<PAGE>

     IN WITNESS WHEREOF, Lessor and Lessee have executed and affixed their
respective seals to this indenture and two counterparts hereof, all as of the
day and year first above written.

In the presence of                      ONE NEVADA REALTY TRUST


/s/ Illegible                           By /s/ Joseph Biotti              (SEAL)
-------------------------------------      -------------------------------
                                           Joseph Biotti, Jr., Trustee


                                        MATRITECH, INC.
[Corporate Seal]


Attest: /s/ Illegible                   By /s/ Stephen D. Chubb
        -----------------------------      -------------------------------------
                                           Stephen D. Chubb,
                                           CEO and Chairman


                                        By /s/ David L. Corbet
                                           -------------------------------------
                                           David L. Corbet, President
                                           and Chief Operating Officer


                                      -43-

<PAGE>

                        THE COMMONWEALTH OF MASSACHUSETTS

          ss. Illegible

     Before me personally appeared the above-named Joseph Biotti, Jr. and
acknowledged the foregoing instrument to be his free act and deed as Trustee of
One Nevada Realty Trust, this 10th day of October 1995.


                                        /s/ Illegible
                                        ----------------------------------------
                                        Notary Public

                        THE COMMONWEALTH OF MASSACHUSETTS

Illegible, ss.

     Before me personally appeared Stephen D. Chubb and David L. Corbet, whose
signatures appear above, as they are respectively the CEO and Chairman and
President and Chief Operating Officer of Matritech, Inc., and acknowledged the
foregoing instrument to be the free act and deed of the said corporation.


                                        /s/ Illegible
                                        ----------------------------------------
                                        Notary Public
                                        My commission expires
                                                              ------------------

                                                         (STAMP)


                                      -44-

<PAGE>

                                   "Exhibit A"

                             [RESERVED FOR PREMISES]

                                   "Exhibit B"

                            [RESERVED FOR SITE PLAN]


                                      -45-

<PAGE>

                                       "C"

                   EASEMENTS PERMITTED USES AND RESTRICTIONS

     1. Lessor and all persons having business with Lessee shall have the right
to use, in common with all other tenants of the Project and all persons having
business with such other tenants, all parking areas, driveways and footways on
the Parcel, except only that reasonable areas may be reserved for the exclusive
use of each of the tenants of the several buildings on the Project. Lessee and
its invitees shall be entitled in the aggregate to 56 parking spaces at the
Project.

     2. Lessee shall be entitled to conduct on the Premises the business of
developing, manufacturing, selling and distribution of its cancer diagnostic
tests, related laboratory and research and development work and incidental
accessory uses, including executive and administrative offices for the said
business. In addition to or in lieu of the uses specifically authorized herein,
Lessee may, with Lessor's prior approval which shall not be unreasonably
withheld, delayed or conditioned, utilize the demised premises for any other
lawful purpose permitted as of right in a manufacturing district pursuant to the
zoning ordinances of the City of Newton.

     3. Lessee shall neither discharge any hazardous waste nor have on the
Premises any product prohibited by any statute, ordinance or bylaw or
disapproved by any insurer of the Premises. Nor shall Lessee cause any danger to
the vicinity through fire, explosion, wastes or any other cause. Nor shall


                                      -46-

<PAGE>

Lessee create unusual noise, vibration, dust, heat, smoke, fumes, odor or glare
that are observable and offensive beyond the boundaries of the demised premises.

     4. Lessee and its legal representatives, successors, sublessees and assigns
shall be bound by the following restrictions:

          a.   All trucking and vehicular maneuvering shall be contained within
               the Parcel in such a manner that no passage is blocked.

          b.   There shall be no open or outside storage on the Parcel. However,
               Lessee may maintain a dumpster of not more than 10 cubic yard
               capacity in a location approved by Lessor.

          c.   Lessee shall use reasonable care not to damage the exterior
               appearance of the Premises, including landscaping thereon.

          d.   Lessor may from time to time designate certain portions of the
               Parcel for purposes of parking, trucking and vehicle maneuvering
               and/or to bar those activities on certain portions of the Parcel.

          e.   Lessor may from time to time by written instrument in recordable
               form grant variances from any one or more of these restrictions
               where, in Lessor's opinion as certified in the instrument,
               desirable relief can be granted without substantial detriment to
               the development of the Parcel and adjacent property as a
               garden-type industrial center and without substantial detriment
               to the portions thereof theretofore built upon. Lessor's written
               approval of any sign, building, structure, alteration, addition
               or landscaping shall be conclusive evidence that the matter so
               approved is in compliance with these restrictions. The term
               Lessor as used herein shall mean the original named Lessor or
               such one successor in title as


                                      -47-

<PAGE>

               may from time to time be expressly granted of record the right to
               enforce these restrictions.

     5. With the prior written approval of Lessor which shall not be
unreasonably withheld, delayed or conditioned and all relevant municipal
authorities, Lessee shall have the right to erect signs, up to 100 square feet,
on the exterior of the Premises or on the Parcel. However, no sign larger than
four square feet in area shall contain anything other than the names and
trademarks of occupants of the Building and such occupants' principal products
or suppliers. Lessor may remove any placard or sign affixed without Lessor prior
written approval or otherwise in violation of the foregoing restrictions.

     6. Certificate of Title, Memoranda of Encumbrances, attached hereto (No.
171784, 6 pages).


                                      -48-
<PAGE>

                                       "D"

                              PART I: LESSOR'S WORK

1.   Installation of scissor jack or similar device to allow loading and
     unloading of trucks in front of freight elevator.

2.   Remove and relocate bench as per attached print, Exhibit CA.

3.   Hook up/make operational all electrical service in the Premises.

4.   Clean and paint manufacturing area, as shown on Exhibit CA.

5.   Make security system operational.

6.   Provide access to neutralization system on first floor.

7.   Put up 2 walls to divide Quality Control Lab, formulation and aseptic fill
     area per attached print CA. Put in heavy 3-foot door to connect formulation
     to aseptic fill.

8.   Put in vinyl ceilings in aseptic area per attached print CA.

9.   Room-off electrical panels in autoclave area.

10.  Provide caging to separate storage 1 and 2 areas per print CA.

11.  Provide caging per print in room between autoclave and packaging per print.

12.  Provide caging in room next to large refrigerator - print shows 5'x7' but
     would like caging to extend 6'x16'.

13.  Provide one shower in women's and men's rooms in manufacturing area,

                  PART II: PREPARATION OF RESEARCH LABORATORIES

1.   Per print CA, in laboratory next to isolation laboratory, remove existing
     partition and wall.

2.   In new storage room provide 2 new 3-foot wide doors and remove door
     connecting storage room to existing area in manufacturing.

3.   Install revolving door in dark room.


                                      -49-

<PAGE>

4.   Remove wall between lunch and office to expand lunch room per print CA.

5.   Put up wall in small lab off main laboratory per print CA.

6.   Storage area is actually animal room; need dedicated heating and air
     conditioning unit in storage room (animal room); put up separating wall per
     print on 5/24/95.


                                      -50-