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                                                                    EXHIBIT 10.1

                            IMARX THERAPEUTICS, INC.

                                 2000 STOCK PLAN

     1. Purposes of the Plan. The purposes of this Stock Plan are to attract and
retain the best available personnel for positions of substantial responsibility,
to provide additional incentive to Employees, Directors and Consultants and to
promote the success of the Company's business. Options granted under the Plan
may be Incentive Stock Options or Nonstatutory Stock Options, as determined by
the Administrator at the time of grant. Stock Purchase Rights may also be
granted under the Plan.

     2. Definitions. As used herein, the following definitions shall apply:

          (a) "Administrator" means the Board or any of its Committees as shall
be administering the Plan in accordance with Section 4 hereof.

          (b) "Applicable Laws" means the requirements relating to the
administration of stock option plans under U.S. state corporate laws, U.S.
federal and state securities laws, the Code, any stock exchange or quotation
system on which the Common Stock is listed or quoted and the applicable laws of
any other country or jurisdiction where Options or Stock Purchase Rights are
granted under the Plan.

          (c) "Board" means the Board of Directors of the Company.

          (d) "Code" means the Internal Revenue Code of 1986, as amended.

          (e) "Committee" means a committee of Directors appointed by the Board
in accordance with Section 4 hereof.

          (f) "Common Stock" means the Common Stock of the Company.

          (g) "Company" means ImaRx Therapeutics, Inc., an Arizona corporation.

          (h) "Consultant" means any person who is engaged by the Company or any
Parent or Subsidiary to render consulting or advisory services to such entity.

          (i) "Director" means a member of the Board of Directors of the
Company.

          (j) "Disability" means total and permanent disability as defined in
Section 22(e)(3) of the Code.

          (k) "Employee" means any person, including Officers and Directors,
employed by the Company or any Parent or Subsidiary of the Company. A Service
Provider shall not cease to be an Employee in the case of (i) any leave of
absence approved by the Company or (ii) transfers between locations of the
Company or between the Company, its Parent, any Subsidiary, or any


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successor. For purposes of Incentive Stock Options, no such leave may exceed
ninety days, unless reemployment upon expiration of such leave is guaranteed by
statute or contract. If reemployment upon expiration of a leave of absence
approved by the Company is not so guaranteed, on the 181st day of such leave any
Incentive Stock Option held by the Optionee shall cease to be treated as an
Incentive Stock Option and shall be treated for tax purposes as a Nonstatutory
Stock Option. Neither service as a Director nor payment of a director's fee by
the Company shall be sufficient to constitute "employment" by the Company.

          (l) "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

          (m) "Fair Market Value" means, as of any date, the value of Common
Stock determined as follows:

               (i) If the Common Stock is listed on any established stock
exchange or a national market system, including without limitation the Nasdaq
National Market or The Nasdaq Small Cap Market of The Nasdaq Stock Market, its
Fair Market Value shall be the closing sales price for such stock (or the
closing bid, if no sales were reported) as quoted on such exchange or system for
the last market trading day prior to the time of determination, as reported in
The Wall Street Journal or such other source as the Administrator deems
reliable;

               (ii) If the Common Stock is regularly quoted by a recognized
securities dealer but selling prices are not reported, its Fair Market Value
shall be the mean between the high bid and low asked prices for the Common Stock
on the last market trading day prior to the day of determination; or

               (iii) In the absence of an established market for the Common
Stock, the Fair Market Value thereof shall be determined in good faith by the
Administrator.

          (n) "Incentive Stock Option" means an Option intended to qualify as an
incentive stock option within the meaning of Section 422 of the Code.

          (o) "Nonstatutory Stock Option" means an Option not intended to
qualify as an Incentive Stock Option.

          (p) "Officer" means a person who is an officer of the Company within
the meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

          (q) "Option" means a stock option granted pursuant to the Plan.

          (r) "Option Agreement" means a written or electronic agreement between
the Company and an Optionee evidencing the terms and conditions of an individual
Option grant. The Option Agreement is subject to the terms and conditions of the
Plan.

          (s) "Option Exchange Program" means a program whereby outstanding
Options are exchanged for Options with a lower exercise price.


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          (t) "Optioned Stock" means the Common Stock subject to an Option or a
Stock Purchase Right.

          (u) "Optionee" means the holder of an outstanding Option or Stock
Purchase Right granted under the Plan.

          (v) "Parent" means a "parent corporation," whether now or hereafter
existing, as defined in Section 424(e) of the Code.

          (w) "Plan" means this 2000 Stock Plan.

          (x) "Restricted Stock" means shares of Common Stock acquired pursuant
to a grant of a Stock Purchase Right under Section 11 below.

          (y) "Service Provider" means an Employee, Director or Consultant.

          (z) "Share" means a share of the Common Stock, as adjusted in
accordance with Section 12 below.

          (aa) "Stock Purchase Right" means a right to purchase Common Stock
pursuant to Section 11 below.

          (bb) "Subsidiary" means a "subsidiary corporation," whether now or
hereafter existing, as defined in Section 424(f) of the Code.

     3. Stock Subject to the Plan. Subject to the provisions of Section 12 of
the Plan, the maximum aggregate number of Shares that may be subject to option
and sold under the Plan is 3,000,000 Shares. The Shares may be authorized but
unissued, or reacquired Common Stock.

     If an Option or Stock Purchase Right expires or becomes unexercisable
without having been exercised in full, or is surrendered pursuant to an Option
Exchange Program, the unpurchased Shares which were subject thereto shall become
available for future grant or sale under the Plan (unless the Plan has
terminated). However, Shares that have actually been issued under the Plan, upon
exercise of either an Option or Stock Purchase Right, shall not be returned to
the Plan and shall not become available for future distribution under the Plan,
except that if Shares of Restricted Stock are repurchased by the Company at
their original purchase price, such Shares shall become available for future
grant under the Plan.

     4. Administration of the Plan.

          (a) Administrator. The Plan shall be administered by the Board or a
Committee appointed by the Board, which Committee shall be constituted to comply
with Applicable Laws.

          (b) Powers of the Administrator. Subject to the provisions of the Plan
and, in the case of a Committee, the specific duties delegated by the Board to
such Committee, and subject to the approval of any relevant authorities, the
Administrator shall have the authority in its discretion:


                                                                               3

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               (i) to determine Fair Market Value;

               (ii) to select the Service Providers to whom Options and Stock
Purchase Rights may from time to time be granted hereunder;

               (iii) to determine the number of Shares to be covered by each
such award granted hereunder;

               (iv) to approve forms of agreement for use under the Plan;

               (v) to determine the terms and conditions, of any Option or Stock
Purchase Right granted hereunder. Such terms and conditions include, but are not
limited to, the exercise price, the time or times when Options or Stock Purchase
Rights may be exercised (which may be based on performance criteria), any
vesting acceleration or waiver of forfeiture restrictions, and any restriction
or limitation regarding any Option or Stock Purchase Right or the Common Stock
relating thereto, based in each case on such factors as the Administrator, in
its sole discretion, shall determine;

               (vi) to determine whether and under what circumstances an Option
may be settled in cash under subsection 9(e) instead of Common Stock;

               (vii) to reduce the exercise price of any Option to the then
current Fair Market Value if the Fair Market Value of the Common Stock covered
by such Option has declined since the date the Option was granted;

               (viii) to initiate an Option Exchange Program;

               (ix) to prescribe, amend and rescind rules and regulations
relating to the Plan, including rules and regulations relating to sub-plans
established for the purpose of qualifying for preferred tax treatment under
foreign tax laws;

               (x) to allow Optionees to satisfy withholding tax obligations by
electing to have the Company withhold from the Shares to be issued upon exercise
of an Option or Stock Purchase Right that number of Shares having a Fair Market
Value equal to the amount required to be withheld. The Fair Market Value of the
Shares to be withheld shall be determined on the date that the amount of tax to
be withheld is to be determined. All elections by Optionees to have Shares
withheld for this purpose shall be made in such form and under such conditions
as the Administrator may deem necessary or advisable; and

               (xi) to construe and interpret the terms of the Plan and awards
granted pursuant to the Plan.

          (c) Effect of Administrator's Decision. All decisions, determinations
and interpretations of the Administrator shall be final and binding on all
Optionees.


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     5. Eligibility.

          (a) Nonstatutory Stock Options and Stock Purchase Rights may be
granted to Service Providers. Incentive Stock Options may be granted only to
Employees.

          (b) Each Option shall be designated in the Option Agreement as either
an Incentive Stock Option or a Nonstatutory Stock Option. However,
notwithstanding such designation, to the extent that the aggregate Fair Market
Value of the Shares with respect to which Incentive Stock Options are
exercisable for the first time by the Optionee during any calendar year (under
all plans of the Company and any Parent or Subsidiary) exceeds $100,000, such
Options shall be treated as Nonstatutory Stock Options. For purposes of this
Section 5(b), Incentive Stock Options shall be taken into account in the order
in which they were granted. The Fair Market Value of the Shares shall be
determined as of the time the Option with respect to such Shares is granted.

          (c) Neither the Plan nor any Option or Stock Purchase Right shall
confer upon any Optionee any right with respect to continuing the Optionee's
relationship as a Service Provider with the Company, nor shall it interfere in
any way with his or her right or the Company's right to terminate such
relationship at any time, with or without cause.

     6. Term of Plan. The Plan shall become effective upon its adoption by the
Board. It shall continue in effect for a term of ten (10) years unless sooner
terminated under Section 14 of the Plan.

     7. Term of Option. The term of each Option shall be stated in the Option
Agreement; provided, however, that the term shall be no more than ten (10) years
from the date of grant thereof. In the case of an Incentive Stock Option granted
to an Optionee who, at the time the Option is granted, owns stock representing
more than ten percent (10%) of the voting power of all classes of stock of the
Company or any Parent or Subsidiary, the term of the Option shall be five (5)
years from the date of grant or such shorter term as may be provided in the
Option Agreement.

     8. Option Exercise Price and Consideration.

          (a) The per share exercise price for the Shares to be issued upon
exercise of an Option shall be such price as is determined by the Administrator,
but shall be subject to the following:

               (i) In the case of an Incentive Stock Option

                    (A) granted to an Employee who, at the time of grant of such
Option, owns stock representing more than ten percent (10%) of the voting power
of all classes of stock of the Company or any Parent or Subsidiary, the exercise
price shall be no less than 110% of the Fair Market Value per Share on the date
of grant.

                    (B) granted to any other Employee, the per Share exercise
price shall be no less than 100% of the Fair Market Value per Share on the date
of grant.


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               (ii) In the case of a Nonstatutory Stock Option

                    (A) granted to a Service Provider who, at the time of grant
of such Option, owns stock representing more than ten percent (10%) of the
voting power of all classes of stock of the Company or any Parent or Subsidiary,
the exercise price shall be no less than 110% of the Fair Market Value per Share
on the date of grant.

                    (B) granted to any other Service Provider, the per Share
exercise price shall be no less than 85% of the Fair Market Value per Share on
the date of grant.

               (iii) Notwithstanding the foregoing, Options may be granted with
a per Share exercise price other than as required above pursuant to a merger or
other corporate transaction.

          (b) The consideration to be paid for the Shares to be issued upon
exercise of an Option, including the method of payment, shall be determined by
the Administrator (and, in the case of an Incentive Stock Option, shall be
determined at the time of grant). Such consideration may consist of (1) cash,
(2) check, (3) promissory note, (4) other Shares which (x) in the case of Shares
acquired upon exercise of an Option, have been owned by the Optionee for more
than six months on the date of surrender, and (y) have a Fair Market Value on
the date of surrender equal to the aggregate exercise price of the Shares as to
which such Option shall be exercised, (5) consideration received by the Company
under a cashless exercise program implemented by the Company in connection with
the Plan, or (6) any combination of the foregoing methods of payment. In making
its determination as to the type of consideration to accept, the Administrator
shall consider if acceptance of such consideration may be reasonably expected to
benefit the Company.

     9. Exercise of Option.

          (a) Procedure for Exercise; Rights as a Shareholder. Any Option
granted hereunder shall be exercisable according to the terms hereof at such
times and under such conditions as determined by the Administrator and set forth
in the Option Agreement. Except in the case of Options granted to Officers,
Directors and Consultants, Options shall become exercisable at a rate of no less
than 20% per year over five (5) years from the date the Options are granted.
Unless the Administrator provides otherwise, vesting of Options granted
hereunder to Officers and Directors shall be tolled during any unpaid leave of
absence. An Option may not be exercised for a fraction of a Share.

               An Option shall be deemed exercised when the Company receives:
(i) written or electronic notice of exercise (in accordance with the Option
Agreement) from the person entitled to exercise the Option, and (ii) full
payment for the Shares with respect to which the Option is exercised. Full
payment may consist of any consideration and method of payment authorized by the
Administrator and permitted by the Option Agreement and the Plan. Shares issued
upon exercise of an Option shall be issued in the name of the Optionee or, if
requested by the Optionee, in the name of the Optionee and his or her spouse.
Until the Shares are issued (as evidenced by the appropriate entry on the books
of the Company or of a duly authorized transfer agent of the Company), no right
to vote or receive dividends or any other rights as a shareholder shall exist
with respect to the Shares,


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notwithstanding the exercise of the Option. The Company shall issue (or cause to
be issued) such Shares promptly after the Option is exercised. No adjustment
will be made for a dividend or other right for which the record date is prior to
the date the Shares are issued, except as provided in Section 12 of the Plan.

               Exercise of an Option in any manner shall result in a decrease in
the number of Shares thereafter available, both for purposes of the Plan and for
sale under the Option, by the number of Shares as to which the Option is
exercised.

          (b) Termination of Relationship as a Service Provider. If an Optionee
ceases to be a Service Provider, such Optionee may exercise his or her Option
within such period of time as is specified in the Option Agreement (of at least
thirty (30) days) to the extent that the Option is vested on the date of
termination (but in no event later than the expiration of the term of the Option
as set forth in the Option Agreement). In the absence of a specified time in the
Option Agreement, the Option shall remain exercisable for three (3) months
following the Optionee's termination. If, on the date of termination, the
Optionee is not vested as to his or her entire Option, the Shares covered by the
unvested portion of the Option shall revert to the Plan. If, after termination,
the Optionee does not exercise his or her Option within the time specified by
the Administrator, the Option shall terminate, and the Shares covered by such
Option shall revert to the Plan.

          (c) Disability of Optionee. If an Optionee ceases to be a Service
Provider as a result of the Optionee's Disability, the Optionee may exercise his
or her Option within such period of time as is specified in the Option Agreement
(of at least six (6) months) to the extent the Option is vested on the date of
termination (but in no event later than the expiration of the term of such
Option as set forth in the Option Agreement). In the absence of a specified time
in the Option Agreement, the Option shall remain exercisable for twelve (12)
months following the Optionee's termination. If, on the date of termination, the
Optionee is not vested as to his or her entire Option, the Shares covered by the
unvested portion of the Option shall revert to the Plan. If, after termination,
the Optionee does not exercise his or her Option within the time specified
herein, the Option shall terminate, and the Shares covered by such Option shall
revert to the Plan.

          (d) Death of Optionee. If an Optionee dies while a Service Provider,
the Option may be exercised within such period of time as is specified in the
Option Agreement (of at least six (6) months) to the extent that the Option is
vested on the date of death (but in no event later than the expiration of the
term of such Option as set forth in the Option Agreement) by the Optionee's
estate or by a person who acquires the right to exercise the Option by bequest
or inheritance. In the absence of a specified time in the Option Agreement, the
Option shall remain exercisable for twelve (12) months following the Optionee's
termination. If, at the time of death, the Optionee is not vested as to the
entire Option, the Shares covered by the unvested portion of the Option shall
immediately revert to the Plan. If the Option is not so exercised within the
time specified herein, the Option shall terminate, and the Shares covered by
such Option shall revert to the Plan.

          (e) Buyout Provisions. The Administrator may at any time offer to buy
out for a payment in cash or Shares, an Option previously granted, based on such
terms and conditions as the Administrator shall establish and communicate to the
Optionee at the time that such offer is made.


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     10. Non-Transferability of Options and Stock Purchase Rights. The Options
and Stock Purchase Rights may not be sold, pledged, assigned, hypothecated,
transferred, or disposed of in any manner other than by will or by the laws of
descent or distribution and may be exercised, during the lifetime of the
Optionee, only by the Optionee.

     11. Stock Purchase Rights.

          (a) Rights to Purchase. Stock Purchase Rights may be issued either
alone, in addition to, or in tandem with other awards granted under the Plan
and/or cash awards made outside of the Plan. After the Administrator determines
that it will offer Stock Purchase Rights under the Plan, it shall advise the
offeree in writing or electronically of the terms, conditions and restrictions
related to the offer, including the number of Shares that such person shall be
entitled to purchase, the price to be paid, and the time within which such
person must accept such offer. The terms of the offer shall comply in all
respects with A.L.. The offer shall be accepted by execution of a Restricted
Stock purchase agreement in the form determined by the Administrator.

          (b) Repurchase Option. Unless the Administrator determines otherwise,
the Restricted Stock purchase agreement shall grant the Company a repurchase
option exercisable upon the voluntary or involuntary termination of the
purchaser's service with the Company for any reason (including death or
disability). The purchase price for Shares repurchased pursuant to the
Restricted Stock purchase agreement shall be the original price paid by the
purchaser and may be paid by cancellation of any indebtedness of the purchaser
to the Company. The repurchase option shall lapse at such rate as the
Administrator may determine. Except with respect to Shares purchased by
Officers, Directors and Consultants, the repurchase option shall in no case
lapse at a rate of less than 20% per year over five (5) years from the date of
purchase.

          (c) Other Provisions. The Restricted Stock purchase agreement shall
contain such other terms, provisions and conditions not inconsistent with the
Plan as may be determined by the Administrator in its sole discretion.

          (d) Rights as a Shareholder. Once the Stock Purchase Right is
exercised, the purchaser shall have rights equivalent to those of a shareholder
and shall be a shareholder when his or her purchase is entered upon the records
of the duly authorized transfer agent of the Company. No adjustment shall be
made for a dividend or other right for which the record date is prior to the
date the Stock Purchase Right is exercised, except as provided in Section 12 of
the Plan.

     12. Adjustments Upon Changes in Capitalization, Merger or Asset Sale.

          (a) Changes in Capitalization. Subject to any required action by the
shareholders of the Company, the number of shares of Common Stock covered by
each outstanding Option or Stock Purchase Right, and the number of shares of
Common Stock which have been authorized for issuance under the Plan but as to
which no Options or Stock Purchase Rights have yet been granted or which have
been returned to the Plan upon cancellation or expiration of an Option or Stock
Purchase Right, as well as the price per share of Common Stock covered by each
such outstanding Option or Stock Purchase Right, shall be proportionately
adjusted for any increase or decrease in the


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number of issued shares of Common Stock resulting from a stock split, reverse
stock split, stock dividend, combination or reclassification of the Common
Stock, or any other increase or decrease in the number of issued shares of
Common Stock effected without receipt of consideration by the Company. The
conversion of any convertible securities of the Company shall not be deemed to
have been "effected without receipt of consideration." Such adjustment shall be
made by the Board, whose determination in that respect shall be final, binding
and conclusive. Except as expressly provided herein, no issuance by the Company
of shares of stock of any class, or securities convertible into shares of stock
of any class, shall affect, and no adjustment by reason thereof shall be made
with respect to, the number or price of shares of Common Stock subject to an
Option or Stock Purchase Right.

          (b) Dissolution or Liquidation. In the event of the proposed
dissolution or liquidation of the Company, the Administrator shall notify each
Optionee as soon as practicable prior to the effective date of such proposed
transaction. The Administrator in its discretion may provide for an Optionee to
have the right to exercise his or her Option or Stock Purchase Right until
fifteen (15) days prior to such transaction as to all of the Optioned Stock
covered thereby, including Shares as to which the Option or Stock Purchase Right
would not otherwise be exercisable. In addition, the Administrator may provide
that any Company repurchase option applicable to any Shares purchased upon
exercise of an Option or Stock Purchase Right shall lapse as to all such Shares,
provided the proposed dissolution or liquidation takes place at the time and in
the manner contemplated. To the extent it has not been previously exercised, an
Option or Stock Purchase Right will terminate immediately prior to the
consummation of such proposed action.

          (c) Merger or Asset Sale. In the event of a merger of the Company with
or into another corporation, or the sale of substantially all of the assets of
the Company, each outstanding Option and Stock Purchase Right shall be assumed
or an equivalent option or right substituted by the successor corporation or a
Parent or Subsidiary of the successor corporation. In the event that the
successor corporation refuses to assume or substitute for the Option or Stock
Purchase Right, the Optionee shall fully vest in and have the right to exercise
the Option or Stock Purchase Right as to all of the Optioned Stock, including
Shares as to which it would not otherwise be vested or exercisable. If an Option
or Stock Purchase Right becomes fully vested and exercisable in lieu of
assumption or substitution in the event of a merger or sale of assets, the
Administrator shall notify the Optionee in writing or electronically that the
Option or Stock Purchase Right shall be fully exercisable for a period of
fifteen (15) days from the date of such notice, and the Option or Stock Purchase
Right shall terminate upon the expiration of such period. For the purposes of
this paragraph, the Option or Stock Purchase Right shall be considered assumed
if, following the merger or sale of assets, the option or right confers the
right to purchase or receive, for each Share of Optioned Stock subject to the
Option or Stock Purchase Right immediately prior to the merger or sale of
assets, the consideration (whether stock, cash, or other securities or property)
received in the merger or sale of assets by holders of Common Stock for each
Share held on the effective date of the transaction (and if holders were offered
a choice of consideration, the type of consideration chosen by the holders of a
majority of the outstanding Shares); provided, however, that if such
consideration received in the merger or sale of assets is not solely common
stock of the successor corporation or its Parent, the Administrator may, with
the consent of the successor corporation, provide for the consideration to be
received upon the exercise of the Option or Stock Purchase Right, for each Share


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of Optioned Stock subject to the Option or Stock Purchase Right, to be solely
common stock of the successor corporation or its Parent equal in fair market
value to the per share consideration received by holders of Common Stock in the
merger or sale of assets.

     13. Time of Granting Options and Stock Purchase Rights. The date of grant
of an Option or Stock Purchase Right shall, for all purposes, be the date on
which the Administrator makes the determination granting such Option or Stock
Purchase Right, or such other date as is determined by the Administrator. Notice
of the determination shall be given to each Service Provider to whom an Option
or Stock Purchase Right is so granted within a reasonable time after the date of
such grant.

     14. Amendment and Termination of the Plan.

          (a) Amendment and Termination. The Board may at any time amend, alter,
suspend or terminate the Plan.

          (b) Shareholder Approval. The Board shall obtain shareholder approval
of any Plan amendment to the extent necessary and desirable to comply with
Applicable Laws.

          (c) Effect of Amendment or Termination. No amendment, alteration,
suspension or termination of the Plan shall impair the rights of any Optionee,
unless mutually agreed otherwise between the Optionee and the Administrator,
which agreement must be in writing and signed by the Optionee and the Company.
Termination of the Plan shall not affect the Administrator's ability to exercise
the powers granted to it hereunder with respect to Options granted under the
Plan prior to the date of such termination.

     15. Conditions Upon Issuance of Shares.

          (a) Legal Compliance. Shares shall not be issued pursuant to the
exercise of an Option unless the exercise of such Option and the issuance and
delivery of such Shares shall comply with Applicable Laws and shall be further
subject to the approval of counsel for the Company with respect to such
compliance.

          (b) Investment Representations. As a condition to the exercise of an
Option, the Administrator may require the person exercising such Option to
represent and warrant at the time of any such exercise that the Shares are being
purchased only for investment and without any present intention to sell or
distribute such Shares if, in the opinion of counsel for the Company, such a
representation is required.

     16. Inability to Obtain Authority. The inability of the Company to obtain
authority from any regulatory body having jurisdiction, which authority is
deemed by the Company's counsel to be necessary to the lawful issuance and sale
of any Shares hereunder, shall relieve the Company of any liability in respect
of the failure to issue or sell such Shares as to which such requisite authority
shall not have been obtained.


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     17. Reservation of Shares. The Company, during the term of this Plan, shall
at all times reserve and keep available such number of Shares as shall be
sufficient to satisfy the requirements of the Plan.

     18. Shareholder Approval. The Plan shall be subject to approval by the
shareholders of the Company within twelve (12) months after the date the Plan is
adopted. Such shareholder approval shall be obtained in the degree and manner
required under Applicable Laws.


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                            IMARX THERAPEUTICS, INC.

                                 2000 STOCK PLAN

                             STOCK OPTION AGREEMENT

     Unless otherwise defined herein, the terms defined in the 2000 Stock Plan
shall have the same defined meanings in this Stock Option Agreement (the "Option
Agreement").

     19. NOTICE OF STOCK OPTION GRANT

          Optionee's Name:                       SS#:
                           ---------------------      --------------------------

          Optionee's Address:
                              --------------------------------------------------

     You have been granted an option to purchase Common Stock of the Company,
subject to the terms and conditions of the Plan and this Option Agreement, as
follows:

     Grant Number
                                        ----------------------------------------

     Date of Grant
                                        ----------------------------------------

     Vesting Commencement Date
                                        ----------------------------------------

     Exercise Price per Share           $.50

     Total Number of Shares Granted
                                        ----------------------------------------

     Total Exercise Price
                                        ----------------------------------------

     Type of Option:                      X   Incentive Stock Option
                                        -----
                                              Nonstatutory Stock Option
                                        -----
     Term/Expiration Date:
                                        ----------------------------------------

     Exercise and Vesting Schedule:

     This Option shall be exercisable in whole or in part, and shall vest
according to the following vesting schedule:

     25% of the Shares subject to the Option shall vest on the 1st anniversity
of Date of Grant, and 25% of the Shares subject to the Option shall vest on each
successive anniversary of the Vesting Commencement Date, subject to Optionee's
continuing to be a Service Provider on such dates.


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     Termination Period:

     This Option may be exercised, to the extent it is then vested, for three
months after Optionee ceases to be a Service Provider. Upon death or Disability
of the Optionee, this Option may be exercised, to the extent it is then vested,
for one year after Optionee ceases to be Service Provider. In no event shall
this Option be exercised later than the Term/Expiration Date as provided above.

     20. AGREEMENT

          (a) Grant of Option. The Administrator of the Company hereby grants to
the Optionee named in the Notice of Grant (the "Optionee"), an option (the
"Option") to purchase the number of Shares set forth in the Notice of Grant, at
the exercise price per Share set forth in the Notice of Grant (the "Exercise
Price"), and subject to the terms and conditions of the Plan, which is
incorporated herein by reference. Subject to Section 14(c) of the Plan, in the
event of a conflict between the terms and conditions of the Plan and this Option
Agreement, the terms and conditions of the Plan shall prevail.

          If designated in the Notice of Grant as an Incentive Stock Option
("ISO"), this Option is intended to qualify as an Incentive Stock Option as
defined in Section 422 of the Code. Nevertheless, to the extent that it exceeds
the $100,000 rule of Code Section 422(d), this Option shall be treated as a
Nonstatutory Stock Option ("NSO").

          (b) Exercise of Option. This Option shall be exercisable during its
term in accordance with the provisions of Section 9 of the Plan as follows:

               (i) Right to Exercise.

                    (A) Subject to subsections 2(a)(ii) and 2(a)(iii) below,
this Option shall be exercisable cumulatively according to the vesting schedule
set forth in the Notice of Grant. Alternatively, at the election of the
Optionee, this Option may be exercised in whole or in part at any time as to
Shares that have not yet vested. Vested Shares shall not be subject to the
Company's repurchase right (as set forth in the Restricted Stock Purchase
Agreement, attached hereto as Exhibit C-1).

                    (B) As a condition to exercising this Option for unvested
Shares, the Optionee shall execute the Restricted Stock Purchase Agreement.

                    (C) This Option may not be exercised for a fraction of a
Share.

               (ii) Method of Exercise. This Option shall be exercisable by
delivery of an exercise notice in the form attached as Exhibit A (the "Exercise
Notice") which shall state the election to exercise the Option, the number of
Shares with respect to which the Option is being exercised, and such other
representations and agreements as may be required by the Company. The Exercise
Notice shall be accompanied by payment of the aggregate Exercise Price as to all
Exercised Shares. This Option shall be deemed to be exercised upon receipt by
the Company of such fully executed Exercise Notice accompanied by the aggregate
Exercise Price.


                                                                              13

<PAGE>

               No Shares shall be issued pursuant to the exercise of an Option
unless such issuance and such exercise complies with Applicable Laws. Assuming
such compliance, for income tax purposes the Shares shall be considered
transferred to the Optionee on the date on which the Option is exercised with
respect to such Shares.

          (c) Optionee's Representations. In the event the Shares have not been
registered under the Securities Act of 1933, as amended, at the time this Option
is exercised, the Optionee shall, if required by the Company, concurrently with
the exercise of all or any portion of this Option, deliver to the Company his or
her Investment Representation Statement in the form attached hereto as Exhibit
B.

          (d) Lock-Up Period. Optionee hereby agrees that, if so requested by
the Company or any representative of the underwriters (the "Managing
Underwriter") in connection with any registration of the offering of any
securities of the Company under the Securities Act, Optionee shall not sell or
otherwise transfer any Shares or other securities of the Company during the
180-day period (or such other period as may be requested in writing by the
Managing Underwriter and agreed to in writing by the Company) (the "Market
Standoff Period") following the effective date of a registration statement of
the Company filed under the Securities Act. Such restriction shall apply only to
the first registration statement of the Company to become effective under the
Securities Act that includes securities to be sold on behalf of the Company to
the public in an underwritten public offering under the Securities Act. The
Company may impose stop-transfer instructions with respect to securities subject
to the foregoing restrictions until the end of such Market Standoff Period.

          (e) Method of Payment. Payment of the aggregate Exercise Price shall
be by any of the following, or a combination thereof, at the election of the
Optionee:

               (i) cash;

               (ii) check;

               (iii) consideration received by the Company under a formal
cashless exercise program adopted by the Company in connection with the Plan; or

               (iv) surrender of other Shares which, (i) in the case of Shares
acquired upon exercise of an option, have been owned by the Optionee for more
than six (6) months on the date of surrender, and (ii) have a Fair Market Value
on the date of surrender equal to the aggregate Exercise Price of the Exercised
Shares.

          (f) Restrictions on Exercise. This Option may not be exercised until
such time as the Plan has been approved by the shareholders of the Company, or
if the issuance of such Shares upon such exercise or the method of payment of
consideration for such shares would constitute a violation of any Applicable
Law.

          (g) Non-Transferability of Option. This Option may not be transferred
in any manner otherwise than by will or by the laws of descent or distribution
and may be exercised during the


                                                                              14

<PAGE>

lifetime of Optionee only by Optionee. The terms of the Plan and this Option
Agreement shall be binding upon the executors, administrators, heirs, successors
and assigns of the Optionee.

          (h) Term of Option. This Option may be exercised only within the term
set out in the Notice of Grant, and may be exercised during such term only in
accordance with the Plan and the terms of this Option.

          (i) Tax Consequences. Set forth below is a brief summary as of the
date of this Option of some of the federal tax consequences of exercise of this
Option and disposition of the Shares. THIS SUMMARY IS NECESSARILY INCOMPLETE,
AND THE TAX LAWS AND REGULATIONS ARE SUBJECT TO CHANGE. THE OPTIONEE SHOULD
CONSULT A TAX ADVISER BEFORE EXERCISING THIS OPTION OR DISPOSING OF THE SHARES.

               (i) Exercise of NSO. There may be a regular federal income tax
liability upon the exercise of an NSO. The Optionee will be treated as having
received compensation income (taxable at ordinary income tax rates) equal to the
excess, if any, of the Fair Market Value of the Exercised Shares on the date of
exercise over the Exercise Price. If Optionee is an Employee or a former
Employee, the Company will be required to withhold from Optionee's compensation
or collect from Optionee and pay to the applicable taxing authorities an amount
in cash equal to a percentage of this compensation income at the time of
exercise, and may refuse to honor the exercise and refuse to deliver Shares if
such withholding amounts are not delivered at the time of exercise.

               (ii) Exercise of ISO. If this Option qualifies as an ISO, there
will be no regular federal income tax liability upon the exercise of the Option,
although the excess, if any, of the Fair Market Value of the Exercised Shares on
the date of exercise over the Exercise Price will be treated as an adjustment to
the alternative minimum tax for federal tax purposes and may subject the
Optionee to the alternative minimum tax in the year of exercise.

               (iii) Exercise of ISO Following Disability. If the Optionee
ceases to be an Employee as a result of a disability that is not a total and
permanent disability as defined in Section 22(e)(3) of the Code, to the extent
permitted on the date of termination, the Optionee must exercise an ISO within
three months of such termination for the ISO to be qualified as an ISO.

               (iv) Disposition of Shares. In the case of an NSO, if Shares are
held for at least one year, any gain realized on disposition of the Shares will
be treated as long-term capital gain for federal income tax purposes. In the
case of an ISO, if Shares transferred pursuant to the Option are held for at
least one year after exercise and at least two years after the Date of Grant,
any gain realized on disposition of the Shares will also be treated as long-term
capital gain for federal income tax purposes. If Shares purchased under an ISO
are disposed of within one year after exercise or two years after the Date of
Grant, any gain realized on such disposition will be treated as compensation
income (taxable at ordinary income rates) to the extent of the difference
between the Exercise Price of the Exercised Shares and the lesser of (i) the
Fair Market Value of the Exercised Shares on the date of exercise, or (ii) the
sale price of the Exercised Shares. Different rules may apply if the Shares are
subject to a substantial risk of forfeiture (within the meaning of Section 83 of
the Code) at the


                                                                              15

<PAGE>

time of purchase. Any additional gain will be taxed as capital gain, short-term
depending on the period that the ISO Shares were held.

               (v) Notice of Disqualifying Disposition of ISO Shares. If the
Option granted to Optionee herein is an ISO, and if Optionee sells or otherwise
disposes of any of the Shares acquired pursuant to the ISO on or before the
later of (i) the date two years after the Date of Grant, or (ii) the date one
year after the date of exercise, the Optionee shall immediately notify the
Company in writing of such disposition. Optionee agrees that Optionee may be
subject to income tax withholding by the Company on the compensation income
recognized by the Optionee.

               (vi) Section 83(b) Election for Unvested Shares Purchased
Pursuant to Options. With respect to the exercise of an Option for unvested
Shares, an election (the "Election") may be filed by the Optionee with the
Internal Revenue Service, within 30 days of the purchase of the Shares, electing
pursuant to Section 83(b) of the Code to be taxed currently on any difference
between the purchase price of the Shares and their Fair Market Value on the date
of purchase. In the case of an NSO, this will result in a recognition of taxable
income to the Optionee on the date of exercise, measured by the excess, if any,
of the Fair Market Value of the Exercised Shares, at the time the Option is
exercised over the purchase price for the Exercised Shares. Absent such an
election, taxable income will be measured and recognized by Optionee at the time
or times on which the Company's Repurchase Option lapses. In the case of an ISO,
such an election will result in a recognition of income to the Optionee for
alternative minimum tax purposes on the date of exercise, measured by the
excess, if any, of the Fair Market Value of the Exercised Shares, at the time
the Option is exercised, over the purchase price for the Exercised Shares.
Absent such an election, alternative minimum taxable income will be measured and
recognized by Optionee at the time or times on which the Company's Repurchase
Option lapses. Optionee is strongly encouraged to seek the advice of his or her
own tax consultants in connection with the purchase of the Shares and the
advisability of filing of the Election under Section 83(b) of the Code. A form
of Election under Section 83(b) is attached hereto as Exhibit C-5 for reference.

                    OPTIONEE ACKNOWLEDGES THAT IT IS OPTIONEE'S SOLE
RESPONSIBILITY AND NOT THE COMPANY'S TO FILE TIMELY THE ELECTION UNDER SECTION
83(b), EVEN IF OPTIONEE REQUESTS THE COMPANY OR ITS REPRESENTATIVE TO MAKE THIS
FILING ON OPTIONEE'S BEHALF.

          (j) Entire Agreement; Governing Law. The Plan is incorporated herein
by reference. The Plan and this Option Agreement constitute the entire agreement
of the parties with respect to the subject matter hereof and supersede in their
entirety all prior undertakings and agreements of the Company and Optionee with
respect to the subject matter hereof, and may not be modified adversely to the
Optionee's interest except by means of a writing signed by the Company and
Optionee. This Option Agreement is governed by the internal substantive laws but
not the choice of law rules of the State of Arizona.

          (k) No Guarantee of Continued Service. OPTIONEE ACKNOWLEDGES AND
AGREES THAT THE VESTING OF SHARES PURSUANT TO THE VESTING SCHEDULE HEREOF IS
EARNED ONLY BY CONTINUING AS A SERVICE PROVIDER AT THE WILL


                                                                              16

<PAGE>

OF THE COMPANY (NOT THROUGH THE ACT OF BEING HIRED, BEING GRANTED THIS OPTION OR
ACQUIRING SHARES HEREUNDER). OPTIONEE FURTHER ACKNOWLEDGES AND AGREES THAT THIS
AGREEMENT, THE TRANSACTIONS CONTEMPLATED HEREUNDER AND THE VESTING SCHEDULE SET
FORTH HEREIN DO NOT CONSTITUTE AN EXPRESS OR IMPLIED PROMISE OF CONTINUED
ENGAGEMENT AS A SERVICE PROVIDER FOR THE VESTING PERIOD, FOR ANY PERIOD, OR AT
ALL, AND SHALL NOT INTERFERE IN ANY WAY WITH OPTIONEE'S RIGHT OR THE COMPANY'S
RIGHT TO TERMINATE OPTIONEE'S RELATIONSHIP AS A SERVICE PROVIDER AT ANY TIME,
WITH OR WITHOUT CAUSE.

                    Optionee acknowledges receipt of a copy of the Plan and
represents that he or she is familiar with the terms and provisions thereof, and
hereby accepts this Option subject to all of the terms and provisions thereof.
Optionee has reviewed the Plan and this Option in their entirety, has had an
opportunity to obtain the advice of counsel prior to executing this Option and
fully understands all provisions of the Option. Optionee hereby agrees to accept
as binding, conclusive and final all decisions or interpretations of the
Administrator upon any questions arising under the Plan or this Option. Optionee
further agrees to notify the Company upon any change in the residence address
indicated below.

OPTIONEE                                IMARX THERAPEUTICS, INC.


-------------------------------------   ----------------------------------------
Signature                               By Evan C. Unger

-------------------------------------   President & CEO
Print Name                              Title


-------------------------------------
Spouse signature

-------------------------------------
Print Name

-------------------------------------

-------------------------------------
Residence Address


                                                                              17

<PAGE>

                                    EXHIBIT A

                                 2000 STOCK PLAN

                                 EXERCISE NOTICE

                            ImaRx Therapeutics, Inc.
                                 1635 East 18th
                              Tucson, Arizona 85719

     Attention: Stock Plan Administrator

     Exercise of Option. Effective as of today, ________________, ____, the
undersigned ("Optionee") hereby elects to exercise Optionee's option (the
"Option") to purchase ________________ shares of the Common Stock (the "Shares")
of ImaRx Therapeutics, Inc. (the "Company") under and pursuant to the 2000 Stock
Plan (the "Plan") and the Stock Option Agreement dated ______________, _____
(the "Option Agreement").

          (l) Delivery of Payment. Purchaser herewith delivers to the Company
the full purchase price of the Shares, as set forth in the Option Agreement.

          (m) Representations of Optionee. Optionee acknowledges that Optionee
has received, read and understood the Plan and the Option Agreement and agrees
to abide by and be bound by their terms and conditions.

          (n) Rights as Shareholder. Until the issuance of the Shares (as
evidenced by the appropriate entry on the books of the Company or of a duly
authorized transfer agent of the Company), no right to vote or receive dividends
or any other rights as a shareholder shall exist with respect to the optioned
stock, notwithstanding the exercise of the Option. The Shares shall be issued to
the Optionee as soon as practicable after the Option is exercised. No adjustment
shall be made for a dividend or other right for which the record date is prior
to the date of issuance except as provided in Section 12 of the Plan.

          (o) Company's Right of First Refusal. Before any Shares held by
Optionee or any transferee (either being sometimes referred to herein as the
"Holder") may be sold or otherwise transferred (including transfer by gift or
operation of law), the Company or its assignee(s) shall have a right of first
refusal to purchase the Shares on the terms and conditions set forth in this
Section (the "Right of First Refusal").

               (i) Notice of Proposed Transfer. The Holder of the Shares shall
deliver to the Company a written notice (the "Notice") stating: (i) the Holder's
bona fide intention to sell or otherwise transfer such Shares; (ii) the name of
each proposed purchaser or other transferee ("Proposed Transferee"); (iii) the
number of Shares to be transferred to each Proposed Transferee;


                                                                               1

<PAGE>

and (iv) the bona fide cash price or other consideration for which the Holder
proposes to transfer the Shares (the "Offered Price"), and the Holder shall
offer the Shares at the Offered Price to the Company or its assignee(s).

               (ii) Exercise of Right of First Refusal. At any time within
thirty (30) days after receipt of the Notice, the Company and/or its assignee(s)
may, by giving written notice to the Holder, elect to purchase all, but not less
than all, of the Shares proposed to be transferred to any one or more of the
Proposed Transferees, at the purchase price determined in accordance with
subsection (c) below.

               (iii) Purchase Price. The purchase price ("Purchase Price") for
the Shares purchased by the Company or its assignee(s) under this Section shall
be the Offered Price. If the Offered Price includes consideration other than
cash, the cash equivalent value of the non-cash consideration shall be
determined by the Board of Directors of the Company in good faith.

               (iv) Payment. Payment of the Purchase Price shall be made, at the
option of the Company or its assignee(s), in cash (by check), by cancellation of
all or a portion of any outstanding indebtedness of the Holder to the Company
(or, in the case of repurchase by an assignee, to the assignee), or by any
combination thereof within 30 days after receipt of the Notice or in the manner
and at the times set forth in the Notice.

               (v) Holder's Right to Transfer. If all of the Shares proposed in
the Notice to be transferred to a given Proposed Transferee are not purchased by
the Company and/or its assignee(s) as provided in this Section, then the Holder
may sell or otherwise transfer such Shares to that Proposed Transferee at the
Offered Price or at a higher price, provided that such sale or other transfer is
consummated within 120 days after the date of the Notice, that any such sale or
other transfer is effected in accordance with any applicable securities laws and
that the Proposed Transferee agrees in writing that the provisions of this
Section shall continue to apply to the Shares in the hands of such Proposed
Transferee. If the Shares described in the Notice are not transferred to the
Proposed Transferee within such period, a new Notice shall be given to the
Company, and the Company and/or its assignees shall again be offered the Right
of First Refusal before any Shares held by the Holder may be sold or otherwise
transferred.

               (vi) Exception for Certain Family Transfers. Anything to the
contrary contained in this Section notwithstanding, the transfer of any or all
of the Shares during the Optionee's lifetime or on the Optionee's death by will
or intestacy to the Optionee's immediate family or a trust for the benefit of
the Optionee's immediate family shall be exempt from the provisions of this
Section. "Immediate Family" as used herein shall mean spouse, lineal descendant
or antecedent, father, mother, brother or sister. In such case, the transferee
or other recipient shall receive and hold the Shares so transferred subject to
the provisions of this Section, and there shall be no further transfer of such
Shares except in accordance with the terms of this Section.


                                                                               2

<PAGE>

               (vii) Termination of Right of First Refusal. The Right of First
Refusal shall terminate as to any Shares upon the first sale of Common Stock of
the Company to the general public pursuant to a registration statement filed
with and declared effective by the Securities and Exchange Commission under the
Securities Act of 1933, as amended.

               Tax Consultation. Optionee understands that Optionee may suffer
adverse tax consequences as a result of Optionee's purchase or disposition of
the Shares. Optionee represents that Optionee has consulted with any tax
consultants Optionee deems advisable in connection with the purchase or
disposition of the Shares and that Optionee is not relying on the Company for
any tax advice.

               Restrictive Legends and Stop-Transfer Orders.

               (viii) Legends. Optionee understands and agrees that the Company
shall cause the legends set forth below or legends substantially equivalent
thereto, to be placed upon any certificate(s) evidencing ownership of the Shares
together with any other legends that may be required by the Company or by state
or federal securities laws:

                    THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
                    UNDER THE SECURITIES ACT OF 1933 (THE "ACT") AND MAY NOT BE
                    OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR
                    HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER THE ACT OR,
                    IN THE OPINION OF COMPANY COUNSEL SATISFACTORY TO THE ISSUER
                    OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR
                    HYPOTHECATION IS IN COMPLIANCE THEREWITH.

                    THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
                    CERTAIN RESTRICTIONS ON TRANSFER AND RIGHT OF FIRST REFUSAL
                    OPTIONS HELD BY THE ISSUER OR ITS ASSIGNEE(S) AS SET FORTH
                    IN THE EXERCISE NOTICE BETWEEN THE ISSUER AND THE ORIGINAL
                    HOLDER OF THESE SHARES, A COPY OF WHICH MAY BE OBTAINED AT
                    THE PRINCIPAL OFFICE OF THE ISSUER. SUCH TRANSFER
                    RESTRICTIONS AND RIGHT OF FIRST REFUSAL ARE BINDING ON
                    TRANSFEREES OF THESE SHARES.

                    THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO AN
                    AGREEMENT PROVIDING FOR A MARKET STANDOFF RESTRICTION
                    FOLLOWING THE INITIAL PUBLIC OFFERING OF THE COMPANY'S
                    SECURITIES, A COPY OF WHICH IS ON FILE AT THE PRINCIPAL
                    OFFICE OF THE COMPANY.

               (ix) Stop-Transfer Notices. Optionee agrees that, in order to
ensure compliance with the restrictions referred to herein, the Company may
issue appropriate "stop transfer"


                                                                               3

<PAGE>

instructions to its transfer agent, if any, and that, if the Company transfers
its own securities, it may make appropriate notations to the same effect in its
own records.

               (x) Refusal to Transfer. The Company shall not be required (i) to
transfer on its books any Shares that have been sold or otherwise transferred in
violation of any of the provisions of this Exercise Notice or (ii) to treat as
owner of such Shares or to accord the right to vote or pay dividends to any
purchaser or other transferee to whom such Shares shall have been so
transferred.

          (p) Successors and Assigns. The Company may assign any of its rights
under this Exercise Notice to single or multiple assignees, and the terms and
conditions of this Exercise Notice shall inure to the benefit of the successors
and assigns of the Company. Subject to the restrictions on transfer herein set
forth, the terms and conditions of this Exercise Notice shall be binding upon
Optionee and his or her heirs, executors, administrators, successors and
assigns.

          (q) Interpretation. Any dispute regarding the interpretation of this
Exercise Notice shall be submitted by Optionee or by the Company forthwith to
the Administrator which shall review such dispute at its next regular meeting.
The resolution of such a dispute by the Administrator shall be final and binding
on all parties.

          (r) Governing Law. This Exercise Notice is governed by the laws of the
State of Arizona.


                                                                               4

<PAGE>

          (s) Entire Agreement. The Plan and Option Agreement are incorporated
herein by reference. This Exercise Notice, the Plan, the Restricted Stock
Purchase Agreement, the Option Agreement and the Investment Representation
Statement constitute the entire agreement of the parties with respect to the
subject matter hereof and supersede in their entirety all prior undertakings and
agreements of the Company and Optionee with respect to the subject matter
hereof, and may not be modified adversely to the Optionee's interest except by
means of a writing signed by the Company and Optionee.

Submitted by:                           Accepted by:

OPTIONEE                                ImaRx Therapeutics, Inc.


-------------------------------------   ----------------------------------------
Signature                               By Evan C. Unger

-------------------------------------   President & CEO
Print Name                              Its

Address:                                Address:
                                        1635 East 18th Street
-------------------------------------   Tucson, Arizona 85719

-------------------------------------


-------------------------------------
Spouse Signature


-------------------------------------   ----------------------------------------
Signature                               Date received


                                                                               5

<PAGE>

                                    EXHIBIT B

                       INVESTMENT REPRESENTATION STATEMENT

     OPTIONEE : ______________________________

     COMPANY  : IMARX THERAPEUTICS, INC.

     SECURITY : COMMON STOCK

     AMOUNT   : ______________________________

     DATE     : ______________________________

     In connection with the purchase of the above-listed Securities, the
undersigned Optionee represents to the Company the following:

          (i) Optionee is aware of the Company's business affairs and financial
condition and has acquired sufficient information about the Company to reach an
informed and knowledgeable decision to acquire the Securities. Optionee is
acquiring these Securities for investment for Optionee's own account only and
not with a view to, or for resale in connection with, any "distribution" thereof
within the meaning of the Securities Act of 1933, as amended (the "Securities
Act").

          (ii) Optionee acknowledges and understands that the Securities
constitute "restricted securities" under the Securities Act and have not been
registered under the Securities Act in reliance upon a specific exemption
therefrom, which exemption depends upon, among other things, the bona fide
nature of Optionee's investment intent as expressed herein. In this connection,
Optionee understands that, in the view of the Securities and Exchange
Commission, the statutory basis for such exemption may be unavailable if
Optionee's representation was predicated solely upon a present intention to hold
these Securities for the minimum capital gains period specified under tax
statutes, for a deferred sale, for or until an increase or decrease in the
market price of the Securities, or for a period of one year or any other fixed
period in the future. Optionee further understands that the Securities must be
held indefinitely unless they are subsequently registered under the Securities
Act or an exemption from such registration is available. Optionee further
acknowledges and understands that the Company is under no obligation to register
the Securities. Optionee understands that the certificate evidencing the
Securities will be imprinted with a legend which prohibits the transfer of the
Securities unless they are registered or such registration is not required in
the opinion of counsel satisfactory to the Company and with any other legend
required under applicable state securities laws.

          (iii) Optionee is familiar with the provisions of Rule 701 and Rule
144, each promulgated under the Securities Act, which, in substance, permit
limited public resale of "restricted securities" acquired, directly or
indirectly from the issuer thereof, in a non-public offering subject to the
satisfaction of certain conditions. Rule 701 provides that if the issuer
qualifies under Rule 701 at


                                                                               1

<PAGE>

the time of the grant of the Option to the Optionee, the exercise will be exempt
from registration under the Securities Act. In the event the Company becomes
subject to the reporting requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, ninety (90) days thereafter (or such longer period as any
market stand-off agreement may require) the Securities exempt under Rule 701 may
be resold, subject to the satisfaction of certain of the conditions specified by
Rule 144, including: (1) the resale being made through a broker in an
unsolicited "broker's transaction" or in transactions directly with a market
maker (as said term is defined under the Securities Exchange Act of 1934); and,
in the case of an affiliate, (2) the availability of certain public information
about the Company, (3) the amount of Securities being sold during any three
month period not exceeding the limitations specified in Rule 144(e), and (4) the
timely filing of a Form 144, if applicable.

               In the event that the Company does not qualify under Rule 701 at
the time of grant of the Option, then the Securities may be resold in certain
limited circumstances subject to the provisions of Rule 144, which requires the
resale to occur not less than one year after the later of the date the
Securities were sold by the Company or the date the Securities were sold by an
affiliate of the Company, within the meaning of Rule 144; and, in the case of
acquisition of the Securities by an affiliate, or by a non-affiliate who
subsequently holds the Securities less than two years, the satisfaction of the
conditions set forth in sections (1), (2), (3) and (4) of the paragraph
immediately above.

          (iv) Optionee further understands that in the event all of the
applicable requirements of Rule 701 or 144 are not satisfied, registration under
the Securities Act, compliance with Regulation A, or some other registration
exemption will be required; and that, notwithstanding the fact that Rules 144
and 701 are not exclusive, the Staff of the Securities and Exchange Commission
has expressed its opinion that persons proposing to sell private placement
securities other than in a registered offering and otherwise than pursuant to
Rules 144 or 701 will have a substantial burden of proof in establishing that an
exemption from registration is available for such offers or sales, and that such
persons and their respective brokers who participate in such transactions do so
at their own risk. Optionee understands that no assurances can be given that any
such other registration exemption will be available in such event.

                                        Signature of Optionee:


                                        ----------------------------------------

                                        Date:
                                              ----------------------------------


                                                                               2

<PAGE>

                                   EXHIBIT C-1

                            IMARX THERAPEUTICS, INC.

                                 2000 STOCK PLAN

                       RESTRICTED STOCK PURCHASE AGREEMENT

     THIS AGREEMENT is made between __________________________ (the "Purchaser")
and ImaRx Therapeutics, Inc. (the "Company") as of __________________, ____.

     Unless otherwise defined herein, the terms defined in the 2000 Stock Plan
shall have the same defined meanings in this Agreement.

     RECITALS

     A. Pursuant to the exercise of the option (grant number ____) granted to
Purchaser under the Plan and pursuant to the Option Agreement dated
_______________, ____ by and between the Company and Purchaser with respect to
such grant (the "Option"), which Plan and Option Agreement are hereby
incorporated by reference, Purchaser has elected to purchase _________ of those
shares of Common Stock which have not become vested under the vesting schedule
set forth in the Option Agreement ("Unvested Shares"). The Unvested Shares and
the shares subject to the Option Agreement which have become vested are
sometimes collectively referred to herein as the "Shares".

     B. As required by the Option Agreement, as a condition to Purchaser's
election to exercise the option, Purchaser must execute this Agreement, which
sets forth the rights and obligations of the parties with respect to Shares
acquired upon exercise of the Option.

     Repurchase Option.

          If Purchaser's status as a Service Provider is terminated for any
reason, including for cause, death, and Disability, the Company shall have the
right and option to purchase from Purchaser, or Purchaser's personal
representative, as the case may be, all of the Purchaser's Unvested Shares as of
the date of such termination at the price paid by the Purchaser for such Shares
(the "Repurchase Option").

          Upon the occurrence of such termination, the Company may exercise its
Repurchase Option by delivering personally or by registered mail, to Purchaser
(or his transferee or legal representative, as the case may be), within ninety
(90) days of the termination, a notice in writing indicating the Company's
intention to exercise the Repurchase Option and setting forth a date for closing
not later than thirty (30) days from the mailing of such notice. The closing
shall take place at the Company's office. At the closing, the holder of the
certificates for the Unvested Shares being


                                                                               1

<PAGE>

transferred shall deliver the stock certificate or certificates evidencing the
Unvested Shares, and the Company shall deliver the purchase price therefor.

          At its option, the Company may elect to make payment for the Unvested
Shares to a bank selected by the Company. The Company shall avail itself of this
option by a notice in writing to Purchaser stating the name and address of the
bank, date of closing, and waiving the closing at the Company's office.

          If the Company does not elect to exercise the Repurchase Option
conferred above by giving the requisite notice within ninety (90) days following
the termination, the Repurchase Option shall terminate.

          The Repurchase Option shall terminate in accordance with the vesting
schedule contained in Optionee's Option Agreement.

     Transferability of the Shares; Escrow.

          Purchaser hereby authorizes and directs the Secretary of the Company,
or such other person designated by the Company, to transfer the Unvested Shares
as to which the Repurchase Option has been exercised from Purchaser to the
Company.

          To insure the availability for delivery of Purchaser's Unvested Shares
upon repurchase by the Company pursuant to the Repurchase Option under Section
1, Purchaser hereby appoints the Secretary, or any other person designated by
the Company as escrow agent, as its attorney-in-fact to sell, assign and
transfer unto the Company, such Unvested Shares, if any, repurchased by the
Company pursuant to the Repurchase Option and shall, upon execution of this
Agreement, deliver and deposit with the Secretary of the Company, or such other
person designated by the Company, the share certificates representing the
Unvested Shares, together with the stock assignment duly endorsed in blank,
attached hereto as Exhibit C-2. The Unvested Shares and stock assignment shall
be held by the secretary in escrow, pursuant to the Joint Escrow Instructions of
the Company and Purchaser attached as Exhibit C-3 hereto, until the Company
exercises its Repurchase Option, until such Unvested Shares are vested, or until
such time as this Agreement no longer is in effect. As a further condition to
the Company's obligations under this Agreement, the spouse of the Purchaser, if
any, shall execute and deliver to the Company the Consent of Spouse attached
hereto as Exhibit C-4. Upon vesting of the Unvested Shares, the escrow agent
shall promptly deliver to the Purchaser the certificate or certificates
representing such Shares in the escrow agent's possession belonging to the
Purchaser, and the escrow agent shall be discharged of all further obligations
hereunder; provided, however, that the escrow agent shall nevertheless retain
such certificate or certificates as escrow agent if so required pursuant to
other restrictions imposed pursuant to this Agreement.

          The Company, or its designee, shall not be liable for any act it may
do or omit to do with respect to holding the Shares in escrow and while acting
in good faith and in the exercise of its judgment.


                                                                               2

<PAGE>

          Transfer or sale of the Shares is subject to restrictions on transfer
imposed by any applicable state and federal securities laws. Any transferee
shall hold such Shares subject to all the provisions hereof and the Exercise
Notice executed by the Purchaser with respect to any Unvested Shares purchased
by Purchaser and shall acknowledge the same by signing a copy of this Agreement.

     Ownership, Voting Rights, Duties. This Agreement shall not affect in any
way the ownership, voting rights or other rights or duties of Purchaser, except
as specifically provided herein.

     Legends. The share certificate evidencing the Shares issued hereunder shall
be endorsed with the following legend (in addition to any legend required under
applicable federal and state securities laws):

          THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN
          RESTRICTIONS UPON TRANSFER AND RIGHTS OF REPURCHASE AS SET FORTH IN AN
          AGREEMENT BETWEEN THE COMPANY AND THE STOCKHOLDER, A COPY OF WHICH IS
          ON FILE WITH THE SECRETARY OF THE COMPANY.

     Adjustment for Stock Split. All references to the number of Shares and the
purchase price of the Shares in this Agreement shall be appropriately adjusted
to reflect any stock split, stock dividend or other change in the Shares which
may be made by the Company pursuant to Section 12 of the Plan after the date of
this Agreement.

     Notices. Notices required hereunder shall be given in person or by
registered mail to the address of Purchaser shown on the records of the Company,
and to the Company at their respective principal executive offices.

     Survival of Terms. This Agreement shall apply to and bind Purchaser and the
Company and their respective permitted assignees and transferees, heirs,
legatees, executors, administrators and legal successors.

     Section 83(b) Election. Purchaser hereby acknowledges that he or she has
been informed that, with respect to the exercise of an Option for Unvested
Shares, an election (the "Election") may be filed by the Purchaser with the
Internal Revenue Service, within 30 days of the purchase of the exercised
Shares, electing pursuant to Section 83(b) of the Code to be taxed currently on
any difference between the purchase price of the exercised Shares and their Fair
Market Value on the date of purchase. In the case of a Nonstatutory Stock
Option, this will result in a recognition of taxable income to the Purchaser on
the date of exercise, measured by the excess, if any, of the Fair Market Value
of the exercised Shares, at the time the Option is exercised over the purchase
price for the exercised Shares. Absent such an Election, taxable income will be
measured and recognized by Purchaser at the time or times on which the Company's
Repurchase Option lapses. In the case of an Incentive Stock Option, such an
Election will result in a recognition of income to the Purchaser for alternative
minimum tax purposes on the date of exercise, measured by the excess, if any, of
the Fair Market Value of the exercised Shares, at the time the option is
exercised, over the purchase price for the exercised Shares. Absent such an
Election, alternative minimum taxable income will be


                                                                               3

<PAGE>

measured and recognized by Purchaser at the time or times on which the Company's
Repurchase Option lapses. Purchaser is strongly encouraged to seek the advice of
his or her own tax consultants in connection with the purchase of the Shares and
the advisability of filing of the Election under Section 83(b) of the Code. A
form of Election under Section 83(b) is attached hereto as Exhibit C-5 for
reference.

          PURCHASER ACKNOWLEDGES THAT IT IS PURCHASER'S SOLE RESPONSIBILITY AND
NOT THE COMPANY'S TO FILE TIMELY THE ELECTION UNDER SECTION 83(b) OF THE CODE,
EVEN IF PURCHASER REQUESTS THE COMPANY OR ITS REPRESENTATIVE TO MAKE THIS FILING
ON PURCHASER'S BEHALF.

     Representations. Purchaser has reviewed with his own tax advisors the
federal, state, local and foreign tax consequences of this investment and the
transactions contemplated by this Agreement. Purchaser is relying solely on such
advisors and not on any statements or representations of the Company or any of
its agents. Purchaser understands that he (and not the Company) shall be
responsible for his own tax liability that may arise as a result of this
investment or the transactions contemplated by this Agreement.

     Governing Law. This Agreement shall be governed by the internal substantive
laws, but not the choice of law rules, of the State of Arizona.

     Purchaser represents that he has read this Agreement and is familiar with
its terms and provisions. Purchaser hereby agrees to accept as binding,
conclusive and final all decisions or interpretations of the Board upon any
questions arising under this Agreement.


                                                                               4

<PAGE>

     IN WITNESS WHEREOF, this Agreement is deemed made as of the date first set
forth above.

OPTIONEE                                IMARX THERAPEUTICS, INC.


-------------------------------------   By
Signature                                  -------------------------------------

-------------------------------------   Title President & CEO
Print Name


-------------------------------------
Spouse Signature

-------------------------------------
Print Name

-------------------------------------
Residence Address

Dated:
       --------------------, --------


                                                                               5
<PAGE>

                                   EXHIBIT C-2

                      ASSIGNMENT SEPARATE FROM CERTIFICATE

     FOR VALUE RECEIVED I, __________________________, hereby sell, assign and
transfer unto ImaRx Therapeutics, Inc. ______________________ (__________)
shares of the Common Stock of ImaRx Therapeutics, Inc. standing in my name of
the books of said corporation represented by Certificate No. _____ herewith and
do hereby irrevocably constitute and appoint Osborn Maledon, A Professional
Corporation, to transfer the said stock on the books of the within named
corporation with full power of substitution in the premises.

     This Stock Assignment may be used only in accordance with the Restricted
Stock Purchase Agreement between ImaRx Therapeutics, Inc. and the undersigned
dated ______________, _____.


Dated:                    ,             Signature:
       -------------------  ---------              -----------------------------

     INSTRUCTIONS: Please do not fill in any blanks other than the signature
line. The purpose of this assignment is to enable the Company to exercise its
"repurchase option," as set forth in the Agreement, without requiring additional
signatures on the part of the Purchaser.


                                                                               1

<PAGE>

                                   EXHIBIT C-3

                            JOINT ESCROW INSTRUCTIONS

     _________________, ____

Corporate Secretary
ImaRx Therapeutics, Inc.
1635 East 18th Street
Tucson, Arizona 85719

     Dear Sir or Madam:

     As Escrow Agent for both ImaRx Therapeutics, Inc. (the "Company"), and the
undersigned purchaser of stock of the Company (the "Purchaser"), you are hereby
authorized and directed to hold the documents delivered to you pursuant to the
terms of that certain Restricted Stock Purchase Agreement (the "Agreement")
between the Company and the undersigned, in accordance with the following
instructions:

     1. In the event the Company and/or any assignee of the Company (referred to
collectively for convenience herein as the "Company") exercises the Company's
repurchase option set forth in the Agreement, the Company shall give to
Purchaser and you a written notice specifying the number of shares of stock to
be purchased, the purchase price, and the time for a closing hereunder at the
principal office of the Company. Purchaser and the Company hereby irrevocably
authorize and direct you to close the transaction contemplated by such notice in
accordance with the terms of said notice.

     2. At the closing, you are directed (a) to date the stock assignments
necessary for the transfer in question, (b) to fill in the number of shares
being transferred, and (c) to deliver the stock assignments, together with the
certificate evidencing the shares of stock to be transferred, to the Company or
its assignee, against the simultaneous delivery to you of the purchase price (by
cash, a check, or some combination thereof) for the number of shares of stock
being purchased pursuant to the exercise of the Company's repurchase option.

     3. Purchaser irrevocably authorizes the Company to deposit with you any
certificates evidencing shares of stock to be held by you hereunder and any
additions and substitutions to said shares as defined in the Agreement.
Purchaser does hereby irrevocably constitute and appoint you as Purchaser's
attorney-in-fact and agent for the term of this escrow to execute with respect
to such securities all documents necessary or appropriate to make such
securities negotiable and to complete any transaction herein contemplated,
including but not limited to the filing with any applicable state blue sky
authority of any required applications for consent to, or notice of transfer of,
the securities. Subject to the provisions of this paragraph 3, Purchaser shall
exercise all rights and privileges of a stockholder of the Company while the
stock is held by you.


                                                                               1

<PAGE>

     4. Upon written request of the Purchaser, but no more than once per
calendar year, unless the Company's repurchase option has been exercised, you
will deliver to Purchaser a certificate or certificates representing so many
shares of stock as are not then subject to the Company's repurchase option.
Within 120 days after cessation of Purchaser's continuous employment by or
services to the Company, or any parent or subsidiary of the Company, you will
deliver to Purchaser a certificate or certificates representing the aggregate
number of shares held or issued pursuant to the Agreement and not purchased by
the Company or its assignees pursuant to exercise of the Company's repurchase
option.

     5. If at the time of termination of this escrow you should have in your
possession any documents, securities, or other property belonging to Purchaser,
you shall deliver all of the same to Purchaser and shall be discharged of all
further obligations hereunder.

     6. Your duties hereunder may be altered, amended, modified or revoked only
by a writing signed by all of the parties hereto.

     7. You shall be obligated only for the performance of such duties as are
specifically set forth herein and may rely and shall be protected in relying or
refraining from acting on any instrument reasonably believed by you to be
genuine and to have been signed or presented by the proper party or parties. You
shall not be personally liable for any act you may do or omit to do hereunder as
Escrow Agent or as attorney-in-fact for Purchaser while acting in good faith,
and any act done or omitted by you pursuant to the advice of your own attorneys
shall be conclusive evidence of such good faith.

     8. You are hereby expressly authorized to disregard any and all warnings
given by any of the parties hereto or by any other person or corporation,
excepting only orders or process of courts of law and are hereby expressly
authorized to comply with and obey orders, judgments or decrees of any court. In
case you obey or comply with any such order, judgment or decree, you shall not
be liable to any of the parties hereto or to any other person, firm or
corporation by reason of such compliance, notwithstanding any such order,
judgment or decree being subsequently reversed, modified, annulled, set aside,
vacated or found to have been entered without jurisdiction.

     9. You shall not be liable in any respect on account of the identity,
authorities or rights of the parties executing or delivering or purporting to
execute or deliver the Agreement or any documents or papers deposited or called
for hereunder.

     10. You shall not be liable for the outlawing of any rights under the
Statute of Limitations with respect to these Joint Escrow Instructions or any
documents deposited with you.

     11. You shall be entitled to employ such legal counsel and other experts as
you may deem necessary properly to advise you in connection with your
obligations hereunder, may rely upon the advice of such counsel, and may pay
such counsel reasonable compensation therefor.


                                                                               2

<PAGE>

     12. Your responsibilities as Escrow Agent hereunder shall terminate if you
shall cease to be an officer or agent of the Company or if you shall resign by
written notice to each party. In the event of any such termination, the Company
shall appoint a successor Escrow Agent.

     13. If you reasonably require other or further instruments in connection
with these Joint Escrow Instructions or obligations in respect hereto, the
necessary parties hereto shall join in furnishing such instruments.

     14. It is understood and agreed that should any dispute arise with respect
to the delivery and/or ownership or right of possession of the securities held
by you hereunder, you are authorized and directed to retain in your possession
without liability to anyone all or any part of said securities until such
disputes shall have been settled either by mutual written agreement of the
parties concerned or by a final order, decree or judgment of a court of
competent jurisdiction after the time for appeal has expired and no appeal has
been perfected, but you shall be under no duty whatsoever to institute or defend
any such proceedings.

     15. Any notice required or permitted hereunder shall be given in writing
and shall be deemed effectively given upon personal delivery or upon deposit in
the United States Post Office, by registered or certified mail with postage and
fees prepaid, addressed to each of the other parties thereunto entitled at the
following addresses or at such other addresses as a party may designate by ten
days' advance written notice to each of the other parties hereto.

     16. By signing these Joint Escrow Instructions, you become a party hereto
only for the purpose of said Joint Escrow Instructions; you do not become a
party to the Agreement.

     17. This instrument shall be binding upon and inure to the benefit of the
parties hereto, and their respective successors and permitted assigns.


                                                                               3

<PAGE>

     18. These Joint Escrow Instructions shall be governed by the internal
substantive laws, but not the choice of law rules, of Arizona.

PURCHASER                               IMARX THERAPEUTICS, INC.


-------------------------------------
Signature                               By
                                           -------------------------------------

-------------------------------------
Print Name                              Title President & CEO


-------------------------------------
Spouse Signature

-------------------------------------
Print Name

-------------------------------------

-------------------------------------

Residence Address


ESCROW AGENT

-------------------------------------
Corporate Secretary

     Dated:                 ,
            ----------------  -------


                                                                               4
<PAGE>

                                   EXHIBIT C-4

                                CONSENT OF SPOUSE

     I, ____________________, spouse of ___________________, have read and
approve the foregoing Restricted Stock Purchase Agreement (the "Agreement"). In
consideration of granting of the right to my spouse to purchase shares of Common
Stock of ImaRx Therapeutics, Inc., as set forth in the Agreement, I hereby
appoint my spouse as my attorney-in-fact in respect to the exercise of any
rights under the Agreement and agree to be bound by the provisions of the
Agreement insofar as I may have any rights in said Agreement or any shares
issued pursuant thereto under the community property laws or similar laws
relating to marital property in effect in the state of our residence as of the
date of the signing of the foregoing Agreement.


Dated:                    ,             Signature:
      --------------------  ---------              -----------------------------


                                                                               1

<PAGE>

                                   EXHIBIT C-5

        ELECTION UNDER SECTION 83(B) OF THE INTERNAL REVENUE CODE OF 1986

The undersigned taxpayer hereby elects, pursuant to Sections 55 and 83(b) of the
Internal Revenue Code of 1986, as amended, to include in taxpayer's gross income
or alternative minimum taxable income, as the case may be, for the current
taxable year the amount of any compensation taxable to taxpayer in connection
with taxpayer's receipt of the property described below:

1.   The name, address, taxpayer identification number and taxable year of the
     undersigned are as follows:

     NAME: __________________________   TAXPAYER: _________   SPOUSE: __________

     ADDRESS: _______________________

     IDENTIFICATION NO.: ______________ TAXPAYER: ___________ SPOUSE: __________

     TAXABLE YEAR: __________________

2.   The property with respect to which the election is made is described as
     follows: __________ shares (the "Shares") of the Common Stock of ImaRx
     Therapeutics, Inc. (the "Company").

3.   The date on which the property was transferred is: _______________, ______.

4.   The property is subject to the following restrictions:

     The Shares may not be transferred and are subject to forfeiture under the
     terms of an agreement between the taxpayer and the Company. These
     restrictions lapse upon the satisfaction of certain conditions contained in
     such agreement.

5.   The fair market value at the time of transfer, determined without regard to
     any restriction other than a restriction which by its terms will never
     lapse, of such property is: $_________________.

6.   The amount (if any) paid for such property is: $_________________.

     The undersigned has submitted a copy of this statement to the person for
whom the services were performed in connection with the undersigned's receipt of
the above-described property. The transferee of such property is the person
performing the services in connection with the transfer of said property.

     The undersigned understands that the foregoing election may not be revoked
except with the consent of the Commissioner.

     Dated:                 ,
            ----------------  -------   ----------------------------------------
                                        Taxpayer

     The undersigned spouse of taxpayer joins in this election.


                                                                               1

<PAGE>

     Dated:                 ,
            ----------------  -------   ----------------------------------------
                                        Spouse of Taxpayer


                                                                               2