AGREEMENT


               11065 SORRENTO VALLEY COURT, SAN DIEGO, CALIFORNIA

         THIS LEASE ASSIGNMENT AND ASSUMPTION AGREEMENT ("Assignment"),  is made
and entered into this 16th day of April,  1998 (the "Effective  Date"),  between
PHOTOMATRIX IMAGING  CORPORATION,  a Nevada corporation having a mailing address
of 11065 Sorrento  Valley Road,  San Diego,  California  92121,  as successor in
interest to  Photomatrix  Corporation  (the  "Assignor")  and  CRYOGEN,  INC., a
California  corporation having a mailing address of 6199 Cornerstone Court East,
Suite 106, San Diego,  CA 92121 (the  "Assignee").  Mi terms used herein  having
initial capital letters and not otherwise  herein defmed shall have the meanings
ascribed to such terms in the Lease (as defmed below).


                                  WITNESSETH:

          A.  Assinment.  For good and valuable  consideration,  the receipt and
          sufficiency  of are  hereby  acknowledged,  Assignor  hereby  assigns,
          transfers  and conveys to Assignee  all  Assignor's  right,  title and
          interest in and to:

          (i)       that  certain  Standard  Industrial/Commercial  Multi-Tenant
                    Lease  --  Gross,   dated   November  7,  1996  between  THE
                    MANUFACTURERS  LIFE INSURANCE COMPANY (the  "Landlord"),  as
                    lessor,  and Photomatrix  Corporation  ("Lessee")  (Assignor
                    bemg the  successor  to  Lessee),  as  lessee,  relating  to
                    certain  premises located at 11065 Sorrento Valley Road, San
                    Diego,   California  92121,  as  more  particularly  therein
                    described  (the  "Premises"),  a copy of which  is  attached
                    hereto and  incorporated  herein as Exhibit A (the "Lease"),
                    as guaranteed by XSCRIBE CORPORATION (the "Guarantor") under
                    that  certain   Guaranty   dated   November  15,  1996  (the
                    "Guaranty");  and all  advance  rentals  and  other  advance
                    payments made thereunder;



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          (ii)      Assignor's  leasehold  interest in the Premises,  including,
                    without limitation,  any improvements and alterations to the
                    Premises  ("Leasehold  Improvements") which are not owned by
                    Assignor; and

          (iii)     Subject to the provisions of Paragraph Q herein,  Assignor's
                    ownership  interest in category 5 network  cabling,  if any,
                    vertical  blinds and alarm  system  sensors of the  Premises
                    ("Assignor's   Personal   Property")   which  are  owned  by
                    Assignor.

         Assignor  hereby  releases all claims to any prepayment or deposit held
by any person or entity  relating to the Premises,  the  Leasehold  Improvements
(except  relating to the  existing  alarm/telephone  system of the  Premises) or
Assignor's  Personal  Property  (including,   without  limitation,  any  utility
deposits, performance and/or completion bonds, and the like). Ml such




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sums shall be held by such person or entity for the benefit of Assignee, subject
to the  provisions of the  applicable  agreement  requiring  such  prepayment or
deposit.


         B.  Consideration  for  Release  of  Assignor's  Interest  in  Security
Deposit.  Upon the execution of this Assignment,  Assignee shall pay to Assignor
the amount of Nineteen  Thousand  Three Hundred Sixty Dollars  ($19,360.QO),  as
consideration for Assignor's release of its interest in the Security Deposit set
forth in the Lease to Assignee (the "Release Consideration").

         C. Date of Assignment. Assignee hereby accepts the foregoing assignment
and hereby  assumes  primary  liability for and agrees (i) with each of Assignor
and Landlord to perform all of Assignor's  obligations  under the Lease accruing
from and aiter June 8, 1998 (the  "Assignment  Date") and (ii) with  Assignor to
perform all of Assignee's  obligations  under this Assignment  accruing from and
alter the Effective Date. Notwithstanding the Assignment Date, Assignor shall be
solely  responsible  for the payment of Rent until June 15,  1998,  and the June
payment of Rent under the Lease shall be paid as follows: Assignor shall pay the
entire June payment of rent due under the Lease to Landlord on or before June 1,
1998,  and shall  concurrently  deliver to  Assignee a written  request  for the
amount of such payment  attributable on a pro rata basis to the period June 16 -
June 30, 1998  ("Assignee  Initial  Rent  Payment");  within five (5) days after
receiving such written request, Assignee shall pay Assignor the Assignee Initial
Rent  Payment.  Commencing  on July 1, 1998,  and for the  duration of the Lease
term,  Assignee shall make all payments of rent accrumg under the Lease directly
to Landlord.

        D. Delay in Possession.  Notwithstanding  the Assignment  Date set forth
above, if for any reason  Assignor cannot deliver  possession of the Premises to
the  Assignee on said -date for any reason other than a delay caused by Assignee
or a delay in the  receipt of the  Landlord's  consent  hereto,  such  "Assignor
Delay" shall not affect the validity of this  Assignment,  but in such case, the
Assignment  Date shall be delayed,  Assignee's  obligations  hereunder shall not
accrue,  and  Assignor's  obligations  under the Lease shall  continue to accrue
until the  earlier  of the  following  events:  (a) one (1)  business  day after
Assignor  delivers written notice to Assignee that the Premises can be delivered
to Assignee in the physical condition required under this Assignment,  clean and
free of any  assignees  or  occupants  (other than  Assignee)  and any  personal
property of Assignor and any prior assignee or occupant of the Premises  (except
for Assignor's Personal Property); or (b) that date upon which Assignee occupies
the Premises for any Permitted Use other than  construction of Assignee's imtial
tenant  improvements  approved by  Assignor  and  Landlord  or  pre-construction
activities associated therewith.  Notwithstanding the foregoing, Assignor hereby
agrees to use its best efforts to vacate the majority of the Premises  (with the
exception of those certain offices currently  occupied by Assignor's  accounting
and administrative  staff) no later than May 8, 1998. The Assignor shall deliver
the entire Premises to Assignee within two (2) days following  completion of the
FY 1997-98 audit of Assignor,  but no later than June 8,1998. If the Assignor is
unable to deliver  the entire  Premises to Assignee on or before June 8, 1998 in
the condition set forth herein solely  because of any Assignor  Delay,  Assignor
will pay to Assignee,  as liquidated  damages (which Assignee and Assignor agree
fairly reflect  Assignee's damages for delays in delivery of the Premises beyond
the anticipated  Assignment  Date),  Two Thousand  Dollars  ($2,000.00) for each
calendar day that Assignor so delays in delivering the Premises to Assignee.  If
possession  of the  Premises is not  delivered  to  Assignee  by June 15,  1998,
Assignee may, at its option, by notice in writing to Assignor (which shall be




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delivered no later than June 25, 1998),  cancel this  Assignment,  m which event
the parties sh be discharged from all obligations hereunder;  and any funds paid
by either party shall be returned to such party, including commissions.

         E.  Condition of Premises.

                  1. Physical Condition. Assignor hereby represents and warrants
that, to the best of Assignor's knowledge, the roof, mechanical systems, windows
and seals,  structural  components of the Premises,  all electrical and plumbing
Systems of the Premises, each portion of the Premises that Assignor is obligated
to repair and maintain under the Lease, and the Assignor's Personal Property are
all in good  operating  condition and repair and, are or will be in good working
condition on the  Assignment  Date;  provided,  ~owever,  that the  existence of
certain minor leaks in the Premises roof previously  disclosed to Assignee shall
not constitute a breach of the foregoing  warranty so long as Assignor continues
to diligently enforce its rights under the Lease to cause the Landlord to repair
such leaks.  Additionally,  Assignor  shall  deliver the Premises to Assignee in
good and  broom-clean  condition,  with all  lighting,  mechanical  and plumbing
systems, and building fmishes in good working order and condition.  The Premises
shall  be  delivered  to  Assignee  in the  foregoing  condition  on the date of
Assignor's  delivery of each portion of the Premises  between the Effective Date
and the Assignment  Date.  Notwithstanding  the foregoing,  Assignee's  physical
inspection  of the  Premises  to  Assignee's  satisfaction  shall be a condition
subsequent to the  effectiveness  of this  Assignment.  Such inspection shall be
performed,  if at all,  prior to April  30,  1998.  In the event  that  Assignee
determines from such physical  inspection that the Premises are not satisfactory
for  Assignee's  use or  occupancy  based  upon the  physical  condition  of the
Premises only,  Assignee shall notify Assignor of such  determination in writing
no later than May 5, 1998, and this Assignment  shall be deemed  cancelled as of
the date of such notice, in which event the parties shall be discharged from all
obligations  hereunder  and  Assignor  shall  return the  Security  Deposit,  if
previously  delivered to Assignor,  to Assignee.  Failure by Assignee to deliver
such notice by said date shall be deemed  Assignee's  acceptance of the Premises
in its existing physical condition on the Assignment Date (with the exception of
any damages caused by Assignor's agents,  employees or contractors occupying the
Premises between the Effective Date and the Assignment Date, which damages shall
be Assignor's obligation to repair in a prompt and diligent manner).

                  2.  Assignor's  Representations  and  Warranties.  As  of  the
Effective Date,  Assignor  represents and warrants that (a) Assignor is lawfully
possessed  of  the  lessee's  interest  in  and  to  the  Lease,  the  Leasehold
Improvements and the Assignor's Personal Property;  ) Assignor has the right and
authority to assign its interest in the Lease and the Leasehold Improvements and
to convey the Assignor's  Personal Property to Assignee;  (c) the Lease attached
hereto as Exhibit A is complete,  unmodified  and in fill force and effect;  (d)
the Premises  have not been  previously  assigned or subleased by Assignor;  (e)
Assignor  is not in  default  under the  Lease  and,  to the best of  Assignor's
knowledge,  Landlord is not in default thereunder,  and Assignor is not aware of
any event or  existing  condition  which,  with the giving of notice  and/or the
passage of time, would constitute such a default; (f) Assignor's interest in the
Lease,  the Leasehold  Improvements  (with the exception of the  alarm/telephone
system of the  Premises,  which is  controlled  by  Paragraph  Q below)  and the
Assignor's  Personal  Property  shall be delivered to Assignee free and clear of
all liens,  encumbrances  and  creditor's  rights held by any party claiming by,
through or under Assignor; and (g) to the best of Assignor's knowledge, the

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Premises is free of any Hazardous  Substances  (other than de minimis amounts in
compliance with Applicable Laws and the Lease, and associated with the operation
and use of Premises,  including,  without  limitation,  cleaning and maintenance
activities).


         F. Assignee's  Indemnity.  As between  Assignor and Assignee,  Assignee
shall be responsible  for the performance bf all obligations of the lessee under
the Lease  accruing from and alter the Assignment  Date (exce~t as  specifically
set forth herein),  for all liabilities arising from Assignee's use or occupancy
of the Premises to the extent  arising from and after the Effective Date and for
all claims,  costs,  expenses and  liabilities  relating to Assignee's  material
breach  of any  term,  condition,  covenant  or  agreement  of the  Lease  to be
performed by Assignee from and after the Assignment Date, and Assignee agrees to
protect,  defend,  indemiiify and hold harmless  Assignor and Guarantor from any
claims,  losses, costs or expenses (including  reasonable counsel fees) suffered
or  incurred  by Assignor or  Guarantor  arising  out of or  resulting  from any
failure  by  Assignee  to  perform  any  such  obligations,   including  without
limitations  the  Hazardous  Substances  obligations  of the Lease  arising from
Assignee's use of any such Hazardous  Substances in the Premises.  The foregoing
indemnification   shall  include  indemnity  against  all  costs,  expenses  and
liabilities  reasonably incurred in connection with any such claim or proceeding
brought thereon,  and the defense thereof, and shall survive the cancellation or
termination of this Assignment.

         G.  Assinor's  Indemnity.  As between  Assignor and Assignee,  Assignor
shall be responsible  for the performance of all obligations of the lessee under
the Lease that accrue prior to the Effective Date, for all  liabilities  arising
from  Assignor's  or Lessee's  use or  occupancy  of the  Premises to the extent
arising prior to the  Assignment  Date and for al~ claims,  costs,  expenses and
liabilities  relating  to  Assignor's  material  breach of any term,  condition,
covenant or  agreement  of the Lease to be  performed  by Assignor or  Guarantor
prior to the Assignment Date, and Assignor agrees to protect,  defend, indemnify
and hold harmless Assignee from any claims, losses, costs or expenses (including
reasonable  counsel  fees)  suffered or  incurred by Assignee  arising out of or
resulting  from any  failure  by  Assignor  or  Guarantor  to  perform  any such
obligations,  including without limitations the Hazardous Substances obligations
of the Lease arising from Assignor's use of any such Hazardous Substances in the
Premises.  The foregoing  indemnification  shall include  indemnity  against all
costs, expenses and liabilities  reasonably incurred in connection with any such
claim or proceeding brought thereon,  and the defense thereof, and shall survive
the cancellation or termination of this Assignment.

         H. Confirmation of Landlord's Liability  Requirements.  As set forth in
Section 12.2 of the Lease,  Assignor and Assignee  hereby  acknowledge and agree
that,   notwithstanding  the  assignment  and  assumption  hereby  accomplished,
Assignor shall remain fully and primarily liable, which liability shall be joint
and several with that of Assignee, for the performance of all obligations of the
lessee under the Lease  accruing from and alter the  Effective  Date and for the
remainder of the Original Term.

         I. Landlord's  Consent.  This Assignment is conditioned upon Landlord's
written  approval of this Assignment  prior to the Assignment  Date. If Landlord
does not consent to this Assignment  prior to the Assignment  Date,  delivery of
possession of the Premises to Assignee  shall be delayed in accordance  with the
provisions of Paragraph D of this Assignment; provided,

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however,  that such delay shall not be considered  an Assignor  Delay so long as
Assignor is diligently  attempting to enforce Assignor's rights under Section 12
of the Lease.  If  Landlord  refuses to  consent to this  Assignment,  then this
Assignment shall be deemed cancelled as of the date of Landlord's notice of such
refusal,  in which event the parties  shall be discharged  from all  obligations
hereunder  and  Assignor  shall  return  the  Security  Deposit,  if  previously
delivered to Assignor,  to Assignee;  provided,  however,  that if Landlord acts
unreasonably in withholding,  delaying or  conditioning  such consent,  Assignor
shall promptly exercise  commercially  reasonable  efforts to enforce Assignor's
rights under Section 12 of the Lease.

         J. Signage.  At Assignor's  cost,  Assignor shall remove its signs from
the  Premises  and perform all repairs  required to restore the  Premises to the
condition required by the Lease as a result of such removal.

         K. Notices. Assignor's and Assignee's address for all notices and other
communications  under  the  Lease  before  the  Assignment  Date  shall be their
respective  addresses set forth in the first paragraph of this  Assignment,  and
after the Assignment Date shall be:


Assignor:             1958 Kellogg
                      Carlsbad, California 92008
                      Attn: Mr. Suren Dutia

with a copy to:   Sullivan, Hill, Lewin, Rez, Engel & LaBazo
                  550 West C Street, Suite 1500
                  San Diego, California 92101
                  Attn:    John R. Engel, Esq.

Assignee:             11065 Sorrento Valley Road
                      San Diego, CA 92121
                      Attn: Mr. Michael Warford

with a copy to:        Brobeck, Phieger & Harrison, LLP
                            550 West C Street, Suite 1300
                            San Diego, CA 92101
                           Attn:    W. Scott Biel, Esq.

          L. Brokers. Assignor shall pay a commission to The Irving Hughes Group
(the  "Broker") in the amount of Twenty  Three  Thousand  Four  Hundred  Dollars
($23,400.00),  fifty  percent  (50%) of which shall be due and payable to Broker
upon Landlord's  consent to this Assignment  following full execution  hereof by
the parties, and fifty percent (50%) of which shall be due and payable to Broker
upon commencement of rent payments by Assignee directly to Landlord.

          M.  Attorneys'  Fees.  Should any party  commence  any legal action or
proceeding against another based on this Assignment,  the prevailing party shall
be entitled to an award of reasonable  attorneys' fees, in addition to any other
relief to which such party would be entitled.


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          N.  Counterparts.  This  instrument  may  be  executed  in  one or mor
counterparts,  each of which shall be deemed an original, but all of which shall
constitute  one and  the  smae  agreement  after  eachparty  has  executed  such
counterpart.

          0. Governing Law. This instrument shall be construed and mterpreted in
accordance with the laws of the State of Califorma.

          P. Binding  Effect.  The provisions  hereof are binding upon and shall
inure to the benefit of the parties hereto and their  respective  successors and
assigns.

          Q. PERSONAL PROPERTY CONVEYANCE

                  1. Use of Leasehold Improvements.  Assignor and Assignee agree
that the following  Assignor's  Personal  Property  shall remain in the Premises
alter the Assignment  Date and shall be conveyed to the Assignee as its sole and
separate  property in accordance with the terms and conditions of this Paragraph
Q to the  Assignment:  the  Premises  category 5 network  cabling;  all vertical
blinds of the Premises; and the Premises alarm system sensors.

                  2.  Purchase  of  Personal   Property.   Effective   upon  the
Assignment Date and following the receipt of Landlord's consent hereto, Assignee
agrees to purchase and Assignor agrees to sell the Assignor's Personal Property.
Assignee  agrees  to  pay  Assignor  the  sum of  Nine  Thousand  Seven  Hundred
Seventy-One and 14/100 Dollars ($9,771.14)  ("Personal Property Purchase Price")
for the Assignor's  Personal Property,  which shall be payable upon the delivery
of a Bill of Sale executed by Assignor, in the form of Exhibit B attached hereto
and incorporated herein ("Bill of Sale"), conveying title to Assignee; provided,
however,  that if the  network  cabling  is not  category  5, then the  Personal
Property Purchase Price shall be reduced to Two Thousand Two Hundred  Ninety-Six
and 63/100 Dollars.  No commission shall be paid to any Broker or third party on
account of the Personal Property Purchase Price.

                  3.  Alarm  Svstem  Lease  or  Purchase.  As part of the  Lease
obligations  of Assignee  and  Assignor  pursuant to this  Assignment,  Assignor
agrees to lease or sell (as  determined  by  Assignee,  and as  permitted by the
applicable vendor and Landlord) to Assignee, and Assignee agrees to lease or buy
from Assignor, the Assignor's interest in the Premises alarm system not conveyed
to Assignee as part of the Assignor's Personal Property (the "Alarm System"). If
Assignee elects to lease the Alarm System, Assignor shall be responsible for the
repair and maintenance of said Alarm System,  and Assignee shall pay Assignor as
rent for such Alarm System  monthly rent of Ninety  Dollars  ($90.00) each month
for the  remainder of the Lease Term.  If Assignee  elects to purchase the Alarm
System  (and  such  purchase  is  permitted  by  the  applicable  vendor(s)  and
Landlord),  such purchase shall be on an "as-is"  basis,  and Assignee shall pay
Assignor a lump sum of Four Thousand  Dollars  ($4,000.00) as the purchase price
for  such  Alarm  System,  which  purchase  price  shall be  amortized  over the
remaiiiing  Term of the Lease  following  the date of  purchase  to reflect  the
depreciation of the Alarm System.

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             [SIGNATURE PAGE TO ASSIGNMENT AND ASSUMPTION AGREEMENT]


         IN  WITNESS  WHEREOF,  each  of the  parties  hereto  has  caused  this
Assignment to be duly executed as of the Effective Date.




"ASSIGNOR"                                   "ASSIGNEE"

PHOTOMATRIX IMAGING CORPORATION              CRYOGEN, INC.

By:_______________________________           By:_______________________________
Name:_____________________________           Name:_____________________________
Title:____________________________           Title:____________________________