<PAGE>

                                                                     EXHIBIT 4.1

                          REGISTRATION RIGHTS AGREEMENT

            This REGISTRATION RIGHTS AGREEMENT (this "Agreement") is entered
into as of June 2, 2004 by and among Stratagene Corporation, a Delaware
corporation formerly known as Stratagene Holding Corporation ("Stratagene"), and
Joseph A. Sorge ("Sorge"), the J. A. Sorge Trust I, the J. A. Sorge Trust II,
the J. A. Sorge Trust III, the J. A. Sorge Trust IV, Biosense Partners, L.P. and
the Joseph A. Sorge Charitable Remainder Trust dated December 26, 2002
(collectively, the "Sorge Entities").

                                    RECITALS

            WHEREAS, Stratagene, SHC Acquisition Sub, Inc., a Delaware
corporation and a wholly owned subsidiary of Stratagene ("Merger Sub"), and
Hycor Biomedical Inc., a Delaware corporation ("Hycor"), previously entered into
that certain Agreement and Plan of Reorganization dated as of July 24, 2003, as
amended by that certain Amendment No. 1 to Agreement and Plan of Reorganization
dated as of December 29, 2003 by and among Stratagene, Merger Sub and Hycor and
as further amended by that certain Amendment No. 2 to Agreement and Plan of
Reorganization dated as of February 25, 2004 by and among Stratagene, Merger Sub
and Hycor (as so amended, the "Merger Agreement"); and

            WHEREAS, in consideration of the Sorge Entities agreeing to vote in
favor of the Merger Agreement and recognizing the limited ability of the Sorge
Entities to sell their shares of Stratagene common stock, par value $0.0001 per
share (the "Common Stock"), following the merger contemplated by the Merger
Agreement, Stratagene agreed to enter into this Agreement to grant the Sorge
Entities certain registration and other rights with respect to the Registrable
Securities (as defined below).

                                    AGREEMENT

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

                                   ARTICLE I.
                                   DEFINITIONS

      1.1 Definitions. As used herein, unless the context otherwise requires,
the following terms have the following respective meanings:

            "Affiliate" means, with respect to any Person, any Person that,
directly or indirectly, controls, is controlled by or is under common control
with such Person. For the purposes of this definition, "control" (including,
with correlative meanings, the terms "controlled by" and "under common control
with"), as used with respect to any Person, shall mean the possession, directly
or indirectly, of the power to direct or cause the direction of the management
and policies of such Person, whether through the ownership of voting securities
or by contract or otherwise.
<PAGE>
            "Certificate of Incorporation" means the Certificate of
Incorporation of Stratagene, as it may be amended or restated hereafter from
time to time.

            "Common Stock" shall have the meaning set forth in the recitals of
this Agreement.

            "Effective Time" shall have the meaning set forth in the Merger
Agreement.

            "Exchange Act" means the Securities Exchange Act of 1934, as
amended, or any similar or successor Federal statute, and the rules and
regulations of the SEC thereunder, all as the same shall be in effect at the
relevant time.

            "Merger Agreement" shall have the meaning set forth in the recitals
of this Agreement.

            "Permitted Transferee" means, with respect to any Sorge Entity, any
sale or other transfer to an Affiliate of such Sorge Entity and with respect to
Sorge, shall also mean any family member or trust for the benefit of Sorge or
any such family member.

            "Person" means and includes an individual, a corporation, a limited
liability company, an association, a partnership, a trust or estate, a
government or any department or agency thereof.

            "Principal Market" means either the Nasdaq National Market or the
Nasdaq SmallCap Market, or if the Common Stock is not then listed on either of
such markets, the principal market or exchange on which the Common Stock is then
listed or traded.

            "Sorge Entities" shall have the meaning set forth in the preamble of
this Agreement.

            "Registrable Securities" means (a) all shares of Common Stock held
by any Sorge Entity on the date hereof and (b) any other shares of Common Stock
issued by way of a stock dividend, stock split or reverse stock split or in
connection with a combination of shares, recapitalization, merger, consolidation
or similar event, with respect to or in exchange for or in replacement of the
shares listed in clause (a). As to any particular Registrable Securities, such
securities shall cease to be Registrable Securities when (i) a registration
statement covering such securities shall have become effective under the
Securities Act and such securities shall have been disposed of in accordance
with such registration statement, (ii) Rule 144 (or any successor provision)
under the Securities Act is available for the sale of all of the Registrable
Securities held by a Sorge Entity during any three (3)-month period without
registration (taking into account the holdings of all Sorge Entities) or (iii)
such securities shall have ceased to be outstanding.

            "Registration Expenses" means all expenses incident to the
registration and disposition of the Registrable Securities pursuant to Section 2
hereof, including, without limitation, all registration, filing and applicable
national securities exchange fees, all fees and expenses of complying with state
securities or blue sky laws (including fees and disbursements of counsel to the
Sorge Entities in connection with "blue sky" qualification of the Registrable


                                       2
<PAGE>
Securities and determination of their eligibility for investment under the laws
of the various jurisdictions), all word processing, duplicating and printing
expenses, all messenger and delivery expenses, the fees and disbursements of
counsel for Stratagene and of its independent public accountants, including the
expenses of "cold comfort" letters or any special audits required by, or
incident to, such registration, all fees and disbursements of underwriters
(other than underwriting discounts and commissions), and all reasonable fees and
expenses of a single counsel to the Sorge Entities and all holders of
Registrable Securities. The Registration Expenses shall not include the Selling
Expenses.

            "SEC" means the Securities and Exchange Commission or any other
governmental authority at the time administering the Securities Act or the
Exchange Act.

            "Securities Act" means the Securities Act of 1933, as amended, or
any similar or successor Federal statute, and the rules and regulations of the
SEC thereunder, all as the same shall be in effect at the relevant time.

            "Selling Expenses" means underwriting discounts, selling fees and
commissions and stock transfer taxes applicable to the Registrable Securities,
which shall be paid by the Sorge Entities.

            "Sorge" shall have the meaning set forth in the preamble of this
Agreement.

            "Sorge Entities" shall have the meaning set forth in the preamble of
this Agreement.

            "Stratagene" shall have the meaning set forth in the preamble of
this Agreement.

                                   ARTICLE II.
                               REGISTRATION RIGHTS

      2.1 Filing of Registration Statement.

            (a) Registration. Within thirty (30) days following its receipt of a
written request from Sorge after the Effective Time, Stratagene shall (i) use
commercially reasonable efforts to file a registration statement under the
Securities Act on Form S-3, or on Form S-1 if Stratagene does not qualify for
Form S-3, covering 2,000,000 shares of Registrable Securities and (ii) if
requested by Sorge, use commercially reasonable efforts to obtain acceleration
of the effective date of the registration statement relating to such
registration.

            (b) Registration Statement Form. Subject to clause (a)(i) above, the
registration under this Section 2.1 shall be on such appropriate registration
form of the SEC as shall be selected by Stratagene and as shall be reasonably
acceptable to Sorge. Stratagene agrees to include in any such registration
statement all information which, in the opinion of counsel to Sorge and counsel
to Stratagene, is necessary or desirable to be included therein. If such counsel
disagree, the opinion of counsel to Stratagene shall be followed.

            (c) Expenses. Stratagene shall pay all Registration Expenses in
connection with the registration of Registrable Securities under this Section
2.1.


                                       3
<PAGE>
      2.2 Incidental Registration.

            (a) Right to Include Registrable Securities. If Stratagene at any
time proposes to register any Common Stock for its own account or for the
account of any other stockholder under the Securities Act by registration on
Form S-1, S-2 or S-3 or any successor or similar form(s) (except registrations
on any such Form or similar form(s) solely for registration of securities in
connection with an employee benefit plan, stock incentive or dividend
reinvestment plan or a merger, acquisition or consolidation or incidental to an
issuance of securities under Rule 144A under the Securities Act), Stratagene
will give prompt written notice to Sorge of its intention to do so and of each
Sorge Entities' rights under this Section 2.2 in connection with each such
proposed registration. At any time or from time to time after the Effective
Time, upon the written request of Sorge (which request shall specify the maximum
number of Registrable Securities intended to be disposed of by the Sorge
Entities), made as promptly as practicable and in any event within ten (10) days
after the receipt of any such notice, Stratagene shall use commercially
reasonable efforts to effect the registration under the Securities Act of all
Registrable Securities which Stratagene has been so requested to register by the
Sorge Entities; provided, however, that if at any time after giving written
notice of their intention to register any securities and prior to the effective
date of the registration statement filed in connection with such registration,
Stratagene shall determine for any reason not to register or to delay
registration of such securities, Stratagene shall give written notice of such
determination and its reasons therefor to Sorge and (i) in the case of a
determination not to register, shall be relieved of its obligation to register
any Registrable Securities in connection with such registration (but not from
any obligation of Stratagene to pay the Registration Expenses in connection
therewith) and (ii) in the case of a determination to delay registering, shall
be permitted to delay registering any Registrable Securities, for such period of
time as the Board of Directors of Stratagene determines. No registration
effected under this Section 2.2 shall relieve Stratagene of its obligation to
effect the registration under Section 2.1.

            (b) Expenses. Stratagene shall pay all Registration Expenses in
connection with any registration requested pursuant to this Section 2.2.

            (c) Right to Withdraw. The Sorge Entities shall have the right to
withdraw their request for inclusion of their Registrable Securities in any
registration statement pursuant to this Section 2.2 at any time by giving
written notice to Stratagene of their request to withdraw.

            (d) Priority in Incidental Registrations. If the managing
underwriter of any underwritten offering shall inform Stratagene by writing of
its belief that the number of Registrable Securities requested to be included in
such registration, when added to the number of other securities to be offered in
such registration, would jeopardize such offering, then Stratagene shall include
in such registration, only that number of such securities, including Registrable
Securities, which the underwriter determines in its sole discretion will not
jeopardize the success of the offering (such securities to be included in the
following priority: (i) first, the securities proposed to be included by
Stratagene, (ii) second, the Registrable Securities requested by the Sorge
Entities to be included in such registration and (iii) third, any other
securities of Stratagene requested to be included in such registration by any
other holders having the right to include securities on a pro rata basis in
accordance with the number of securities proposed to be included by such other
holders). The Sorge Entities agree to reasonably modify this priority to


                                       4
<PAGE>
facilitate private placements by Stratagene or to facilitate the conversion of
Stratagene Notes (as defined in the Merger Agreement).

      2.3 Registration Procedures. When Stratagene effects the registration of
Registrable Securities under the Securities Act required by Section 2.1 and if
and whenever Stratagene is required to effect the registration of any additional
Registrable Securities under the Securities Act as provided in Section 2.2
hereof, Stratagene shall as expeditiously as possible:

            (a) prepare and file with the SEC as soon as practicable the
requisite registration statement to effect such registration (and shall include
all financial statements required by the SEC to be filed therewith) and
thereafter use commercially reasonable efforts to cause such registration
statement to become effective; provided, however, that before filing such
registration statement (including all exhibits) or any amendment or supplement
thereto or comparable statements under securities or blue sky laws of any
jurisdiction, Stratagene shall as promptly as practicable furnish such documents
to Sorge and each underwriter, if any, participating in the offering of the
Registrable Securities and their respective counsel, which documents will be
subject to the review and comments of the Sorge Entities, each underwriter and
their respective counsel;

            (b) notify Sorge of the SEC's requests for amending or supplementing
the registration statement and the prospectus; and prepare and file with the SEC
such amendments and supplements to such registration statement and the
prospectus used in connection therewith as may be necessary to keep such
registration statement effective and to comply with the provisions of the
Securities Act with respect to the disposition of all Registrable Securities
covered by such registration statement for a period of at least twenty four (24)
months or such shorter period as shall be required for the disposition of all of
such Registrable Securities in accordance with the intended method of
distribution thereof;

            (c) furnish, without charge, to Sorge and each underwriter, if any,
such number of conformed copies of such registration statement and of each such
amendment and supplement thereto (in each case including all exhibits), such
number of copies of the prospectus contained in such registration statement
(including each preliminary prospectus and any summary prospectus) and any other
prospectus filed under Rule 424 under the Securities Act, in conformity with the
requirements of the Securities Act, and such other documents, as Sorge and such
underwriters may reasonably request;

            (d) use commercially reasonable efforts (i) to register or qualify
all Registrable Securities and other securities covered by such registration
statement under such securities or blue sky laws of such states of the United
States of America where an exemption is not available and as Sorge or any
managing underwriter shall reasonably request, (ii) to keep such registration or
qualification in effect for so long as such registration statement remains in
effect and (iii) to take any other action which may be reasonably necessary or
advisable to enable Sorge to consummate the disposition in such jurisdictions of
the securities to be sold by the Sorge Entities, except that Stratagene shall
not for any such purpose be required to qualify generally to do business as a
foreign corporation in any jurisdiction wherein it would not but for the
requirements of this subsection (d) be obligated to be so qualified or to
consent to general service of process or subject itself to taxation in any such
jurisdiction;


                                       5
<PAGE>
            (e) use commercially reasonable efforts to cause all Registrable
Securities covered by such registration statement to be registered with or
approved by such other federal or state governmental agencies or authorities as
may be necessary in the opinion of counsel to Stratagene and counsel to Sorge by
virtue of the business and operations of Stratagene to consummate the
disposition of such Registrable Securities;

            (f) in the case of any underwritten offering under Section 2.2,
cause to be furnished to Sorge and each underwriter, if any, participating in
the offering of the securities covered by such registration statement, a signed
counterpart of (i) an opinion of counsel for Stratagene and (ii) a "comfort"
letter signed by the independent public accountants who have certified
Stratagene's or any other entity's financial statements included or incorporated
by reference in such registration statement, covering substantially the same
matters with respect to such registration statement (and the prospectus included
therein) and, in the case of the accountants' comfort letter, with respect to
events subsequent to the date of such financial statements, as is customarily
covered in opinions of issuer's counsel and in accountants' comfort letters
delivered to the underwriters in underwritten public offerings of securities
(and dated the dates such opinions and comfort letters are customarily dated)
and, in the case of the legal opinion, such other legal matters;

            (g) promptly notify the Sorge Entities and each managing
underwriter, if any, participating in the offering of the securities covered by
such registration statement (i) when such registration statement, any
pre-effective amendment, the prospectus or any prospectus supplement related
thereto or post-effective amendment to such registration statement has been
filed, and, with respect to such registration statement or any post-effective
amendment, when the same has become effective, (ii) of any request by the SEC
for amendments or supplements to such registration statement or the prospectus
related thereto or for additional information, (iii) of the issuance by the SEC
of any stop order suspending the effectiveness of such registration statement or
the initiation of any proceedings for that purpose, (iv) of the receipt by
Stratagene of any notification with respect to the suspension of the
qualification of any of the Registrable Securities for sale under the securities
or blue sky laws of any jurisdiction or the initiation of any proceeding for
such purpose, (v) at any time when a prospectus relating thereto is required to
be delivered under the Securities Act, upon discovery that, or upon the
happening of any event as a result of which, the prospectus included in such
registration statement, as then in effect, includes an untrue statement of a
material fact or omits to state any material fact required to be stated therein
or necessary to make the statements therein not misleading, in the light of the
circumstances under which they were made, and in the case of this clause (v), at
the request of Sorge, promptly prepare and furnish to Sorge and each managing
underwriter, if any, participating in the offering of the Registrable
Securities, a reasonable number of copies of a supplement to or an amendment of
such prospectus as may be necessary so that, as thereafter delivered to Sorge,
such prospectus shall not include an untrue statement of a material fact or omit
to state a material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances under which
they were made and (vi) in the case of an underwritten offering, at any time
when the representations and warranties of Stratagene contemplated by Section
2.4 hereof cease to be true and correct;

            (h) use commercially reasonable efforts to comply with all
applicable rules and regulations of the SEC, and make available to its security
holders, as soon as reasonably


                                       6
<PAGE>
practicable, an earnings statement covering a period of at least twelve months
beginning with the first full calendar month after the effective date of such
registration statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 promulgated thereunder;

            (i) provide and cause to be maintained a transfer agent and
registrar for all Registrable Securities covered by such registration statement
from and after a date not later than the effective date of such registration;

            (j) use commercially reasonable efforts to cause all Registrable
Securities covered by such registration statement to be listed on the Principal
Market;

            (k) deliver promptly to counsel to Sorge and each underwriter, if
any, participating in the offering of the Registrable Securities, copies of all
correspondence between the SEC and Stratagene, its counsel or auditors and all
memoranda relating to discussions with the SEC or its staff with respect to such
registration statement;

            (l) use commercially reasonable efforts to obtain the withdrawal of
any order suspending the effectiveness of the registration statement; and

            (m) provide a CUSIP number for all Registrable Securities, no later
than the effective date of the registration statement.

            Stratagene may require Sorge to furnish Stratagene such information
regarding the Sorge Entities and the distribution of the Registrable Securities
as Stratagene may from time to time reasonably request in writing.

            The Sorge Entities agree that upon receipt of any notice from
Stratagene of the happening of any event of the kind described in paragraph
(g)(iii) or (v) of this Section 2.3, the Sorge Entities will, to the extent
appropriate, discontinue their disposition of Registrable Securities pursuant to
the registration statement relating to such Registrable Securities until, in the
case of paragraph (g)(v) of this Section 2.3, their receipt of the copies of the
supplemented or amended prospectus contemplated by paragraph (g)(v) of this
Section 2.3 and, if so directed by Stratagene, will deliver to Stratagene (at
Stratagene's expense) all copies, other than permanent file copies, then in
their possession, of the prospectus relating to such Registrable Securities
current at the time of receipt of such notice. If the disposition by the Sorge
Entities of their securities is discontinued pursuant to the foregoing sentence,
Stratagene shall extend the period of effectiveness of the registration
statement by the number of days during the period from and including the date of
the giving of notice to and including the date when the Sorge Entities shall
have received copies of the supplemented or amended prospectus contemplated by
paragraph (g)(v) of this Section 2.3.

      2.4 Underwritten Offerings. In the case of a registration pursuant to
Section 2.2 hereof, if Stratagene shall have determined to enter into any
underwriting agreement in connection therewith, all of the Registrable
Securities to be included in such registration shall be subject to such
underwriting agreement. In such case, the Sorge Entities shall be party to such
underwriting agreement.


                                       7
<PAGE>
      2.5 Indemnification.

            (a) Indemnification by Stratagene. Stratagene agrees that in the
event of any registration of any of the Registrable Securities under the
Securities Act, Stratagene shall, and hereby does, indemnify and hold harmless
the Sorge Entities, their respective directors, officers, employees, members,
partners, agents and affiliates and each other Person who participates as an
underwriter in the offering or sale of such securities and each other Person, if
any, who controls any Sorge Entity or any such underwriter within the meaning of
the Securities Act, against any losses, claims, damages, or liabilities, joint
or several, to which the Sorge Entities or any such director, officer, employee,
member, partner, agent or affiliate or underwriter or controlling person may
become subject under the Securities Act or otherwise, insofar as such losses,
claims, damages or liabilities, joint or several (or actions or proceedings,
whether commenced or threatened, in respect thereof), arise out of or are based
upon (i) any untrue statement or alleged untrue statement of any material fact
contained in any registration statement under which such securities were
registered under the Securities Act, any preliminary prospectus, final
prospectus or summary prospectus contained therein, or any amendment or
supplement thereto, (ii) any omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein in light of the circumstances in which they were made not misleading or
(iii) any violation by Stratagene of any Federal, state or common law rule or
regulation applicable to Stratagene and relating to action required of or
inaction by Stratagene in connection with any such registration, and Stratagene
shall reimburse the Sorge Entities and each such director, officer, employee,
member, partner, agent or affiliate, underwriter or controlling Person for any
reasonable legal or any other expenses reasonably incurred by them in connection
with investigating or defending any such loss, claim, liability, action or
proceeding; provided, that Stratagene shall not be liable in any such case to
the Sorge Entities or any such director, officer, employee, member, partner,
agent or affiliate, underwriter or controlling Person to the extent that any
such loss, claim, damage, liability (or action or proceeding in respect thereof)
or expense arises out of or is based upon any untrue statement or alleged untrue
statement or omission or alleged omission made in such registration statement,
any such preliminary prospectus, final prospectus, summary prospectus, amendment
or supplement in reliance upon and in conformity with written information
furnished to Stratagene by or on behalf of the Sorge Entities, specifically
stating that it is for use in the preparation thereof. Such indemnity shall
remain in full force regardless of any investigation made by or on behalf of the
Sorge Entities or any such director, officer, employee, member, partner, agent
or affiliate, underwriter or controlling Person and shall survive the transfer
of such securities by the Sorge Entities. Such indemnity shall not extend to any
liability imposed on Sorge as an officer or director of Stratagene, which shall
be made only as permitted by law and by Stratagene's corporate policy.

            (b) Indemnification by the Sorge Entities. The Sorge Entities agree
that in the event of any registration of the Registrable Securities under the
Securities Act, the Sorge Entities shall, and hereby do, indemnify and hold
harmless (in the same manner and to the same extent as set forth in paragraph
(a) of this Section 2.5) Stratagene, and each director of Stratagene, each
officer, employee, agent and affiliate of Stratagene and each other Person, if
any, who controls Stratagene within the meaning of the Securities Act, with
respect to any statement or alleged statement in or omission or alleged omission
from such registration statement, any preliminary prospectus, final prospectus
or summary prospectus contained therein, or any amendment or supplement thereto,
but only to the extent such statement or alleged statement or omission or


                                       8
<PAGE>
alleged omission was made in reliance upon and in conformity with written
information furnished to Stratagene by or on behalf of the Sorge Entities
specifically stating that it is for use in the preparation of such registration
statement, preliminary prospectus, final prospectus, summary prospectus,
amendment or supplement; provided, however, that the liability of the Sorge
Entities under this Section 2.5(b) shall be limited to the amount of proceeds
(net of expenses and underwriting discounts and commissions) received by the
Sorge Entities in the offering giving rise to such liability. Such indemnity
shall remain in full force and effect, regardless of any investigation made by
or on behalf of Stratagene or any such director, officer or controlling Person
and shall survive the transfer of such securities by the Sorge Entities.

            (c) Notices of Claims, etc. Promptly after receipt by an indemnified
party of notice of the commencement of any action or proceeding involving a
claim referred to in the preceding subsections of this Section 2.5, such
indemnified party shall, if a claim in respect thereof is to be made against an
indemnifying party, give written notice to the latter of the commencement of
such action or proceeding; provided, however, that the failure of any
indemnified party to give notice as provided herein shall not relieve the
indemnifying party of its obligations under the preceding subsections of this
Section 2.5, except to the extent that the indemnifying party is actually
prejudiced by such failure to give notice, and shall not relieve the
indemnifying party from any liability which it may have to the indemnified party
otherwise than under this Section 2.5. In case any such action or proceeding is
brought against an indemnified party, the indemnifying party shall be entitled
to participate therein and, unless in the opinion of outside counsel to the
indemnified party a conflict of interest between such indemnified and
indemnifying parties may exist in respect of such claim, to assume the defense
thereof, jointly with any other indemnifying party similarly notified to the
extent that it may wish, with counsel reasonably satisfactory to such
indemnified party; provided, however, that if the defendants in any such action
or proceeding include both the indemnified party and the indemnifying party and
if in the opinion of outside counsel to the indemnified party there may be legal
defenses available to such indemnified party and/or other indemnified parties
which are different from or in addition to those available to the indemnifying
party, the indemnified party or parties shall have the right to select separate
counsel to defend such action or proceeding on behalf of such indemnified party
or parties, provided, further, that the indemnifying party shall be obligated to
pay for only one counsel and one local counsel for all indemnified parties.
After notice from the indemnifying party to such indemnified party of its
election so to assume the defense thereof and approval by the indemnified party
of such counsel, the indemnifying party shall not be liable to such indemnified
party for any legal expenses subsequently incurred by the latter in connection
with the defense thereof other than reasonable costs of investigation (unless
the first proviso in the preceding sentence shall be applicable). No
indemnifying party shall be liable for any settlement of any action or
proceeding effected without its written consent. No indemnifying party shall,
without the consent of the indemnified party (which consent shall not be
unreasonably withheld or delayed), consent to entry of any judgment or enter
into any settlement which does not include as an unconditional term thereof the
giving by the claimant or plaintiff to such indemnified party of a release from
all liability in respect of such claim or litigation.

            (d) Contribution. If the indemnification provided for in this
Section 2.5 shall for any reason be held by a court to be unavailable to an
indemnified party under subsection (a) or (b) hereof in respect of any loss,
claim, damage or liability, or any action in respect thereof, then, in lieu of
the amount paid or payable under subsection (a) or (b) hereof, the indemnified


                                       9
<PAGE>
party and the indemnifying party under subsection (a) or (b) hereof shall
contribute to the aggregate losses, claims, damages and liabilities (including
legal or other expenses reasonably incurred in connection with investigating the
same), (i) in such proportion as is appropriate to reflect the relative fault of
the indemnifying party on the one hand, and the indemnified party on the other,
which resulted in such loss, claim, damage or liability, or action in respect
thereof, with respect to the statements or omissions which resulted in such
loss, claim, damage or liability, or action in respect thereof, as well as any
other relevant equitable considerations or (ii) if the allocation provided by
clause (i) above is not permitted by applicable law or if the allocation
provided in this clause (ii) provides a greater amount to the indemnified party
than clause (i) above, in such proportion as shall be appropriate to reflect not
only the relative fault but also the relative benefits received by the
indemnifying party and the indemnified party from the offering of the securities
covered by such registration statement as well as any other relevant equitable
considerations. The parties hereto agree that it would not be just and equitable
if contributions pursuant to this Section 2.5(d) were to be determined by pro
rata allocation or by any other method of allocation which does not take into
account the equitable considerations referred to in the preceding sentence of
this Section 2.5(d). No Person guilty of fraudulent misrepresentation (within
the meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any Person who was not guilty of such fraudulent
misrepresentation. In addition, no Person shall be obligated to contribute
hereunder any amounts in payment for any settlement of any action or claim
effected without such Person's consent, which consent shall not be unreasonably
withheld or delayed. Notwithstanding anything in this subsection (d) to the
contrary, no indemnifying party (other than Stratagene) shall be required to
contribute any amount in excess of the proceeds (net of expenses and
underwriting discounts and commissions) received by such party from the sale of
the Registrable Securities in the offering to which the losses, claims, damages
or liabilities of the indemnified parties relate.

            (e) Other Indemnification. Indemnification and contribution similar
to that specified in the preceding subsections of this Section 2.5 (with
appropriate modifications) shall be given by Stratagene and the Sorge Entities
with respect to any required registration or other qualification of securities
under any Federal, state or blue sky law or regulation of any governmental
authority. The indemnification agreements contained in this Section 2.5 shall be
in addition to any other rights to indemnification or contribution which any
indemnified party may have pursuant to law or contract and shall remain
operative and in full force and effect regardless of any investigation made by
or on behalf of any indemnified party and shall survive the transfer of any of
the Registrable Securities by the Sorge Entities.

            (f) Indemnification Payments. The indemnification and contribution
required by this Section 2.5 shall be made by periodic payments of the amount
thereof during the course of the investigation or defense, as and when bills are
received or expense, loss, damage or liability is incurred.

      2.6 Unlegended Certificates. In connection with the offering of any
Registrable Securities registered pursuant to this Section 2, Stratagene shall
(a) facilitate the timely preparation and delivery to Sorge and the
underwriters, if any, participating in such offering, of unlegended certificates
representing ownership of such Registrable Securities being sold in such
denominations and registered in such names as requested by Sorge or such
underwriters and (b) instruct any transfer agent and registrar of such
Registrable Securities to release any stop


                                       10
<PAGE>
transfer orders with respect to any such Registrable Securities, effective upon
the closing of a sale pursuant to the registered offering.

      2.7 No Required Sale. Nothing in this Agreement shall be deemed to create
an independent obligation on the part of the Sorge Entities to sell any
Registrable Securities pursuant to any effective registration statement.

      2.8 Rule 144. Stratagene shall use commercially reasonable efforts to
enable holders of Registrable Securities to sell such securities without
registration under the Securities Act within the limitation of the exemptions
provided by (a) Rule 144 of the Securities Act or (b) any similar rule or
regulation hereafter adopted by the SEC, including, without limiting the
generality of the foregoing, filing on a timely basis all reports required to be
filed by the Exchange Act. Upon the request of Sorge, Stratagene will deliver to
the Sorge Entities a written statement as to whether it has complied with such
requirements.

                                  ARTICLE III.
                                  MISCELLANEOUS

      3.1 Notice. All notices, requests, consents and other communications
hereunder to any party shall be deemed to be sufficient if contained in a
written instrument delivered in person or sent by telecopy, nationally
recognized overnight courier or first class registered or certified mail, return
receipt requested, postage prepaid, addressed to such party at such address as
set forth below or as may hereafter be designated in writing by such party to
the other party:

            Address for Stratagene:

                 11011 North Torrey Pines Road
                 La Jolla, California  92037
                 Attention:  Chief Financial Officer

            Address for the Sorge Entities:

                 c/o Joseph A. Sorge
                 144 10th Street
                 Del Mar, California  92014

      3.2 Assignment; Third Party Beneficiaries. This Agreement shall be binding
upon and inure to the benefit of and be enforceable by the parties hereto and
their respective successors and permitted assigns. This Agreement may not be
assigned by Stratagene, without the prior written consent of Sorge. Each of the
Sorge Entities may, at their election, at any time or from time to time, assign
their rights under this Agreement, in whole or in part, but only to a Permitted
Transferee; provided that the Permitted Transferee shall be bound by all
provisions of this Agreement as if the Permitted Transferee were an original
party to this Agreement.

      3.3 Termination. This Agreement shall terminate and be of no further force
and effect on the earlier of (a) ten (10) years from the date of this Agreement
or (b) such time as no Registrable Securities are outstanding. The Sorge
Entities each represent and warrant to and


                                       11
<PAGE>
covenant with Stratagene that the Sorge Entities and their Affiliates will not
engage, directly or indirectly, in any short sales of the Common Stock prior to
the termination of this Agreement.

      3.4 Remedies. The parties hereto agree that money damages or any other
remedy at law would not be sufficient or adequate remedy for any breach or
violation of, or a default under, this Agreement by them and that, in addition
to all other remedies available to them, each of them shall be entitled to an
injunction restraining such breach, violation or default or threatened breach,
violation or default and to any other equitable relief, including, without
limitation, specific performance, without bond or other security being required.
In any action or proceeding brought to enforce any provision of this Agreement
(including the indemnification provisions thereof), the successful party shall
be entitled to recover reasonable attorneys' fees in addition to its costs and
expenses and any other available remedy.

      3.5 No Inconsistent Agreements. Stratagene will not, on or after the date
of this Agreement, enter into any agreement with respect to its securities which
is inconsistent with the rights granted to the Sorge Entities in this Agreement
or otherwise conflicts with the provisions hereof. Stratagene further represents
and warrants that the rights granted to the Sorge Entities hereunder do not in
any way conflict with and are not inconsistent with any other agreements to
which Stratagene is a party or by which it is bound.

      3.6 Amendments. The terms and provisions of this Agreement may be modified
or amended, or any of the provisions hereof waived, temporarily or permanently,
in a writing executed and delivered by Stratagene and Sorge.

      3.7 Waiver. No waiver of any of the provisions of this Agreement shall be
deemed to or shall constitute a waiver of any other provision hereof (whether or
not similar). No delay on the part of any party in exercising any right, power
or privilege hereunder shall operate as a waiver thereof.

      3.8 Headings. The headings of the sections of this Agreement have been
inserted for convenience of reference only and shall not be deemed to be a part
of this Agreement.

      3.9 Nouns and Pronouns. Whenever the context may require, any pronouns
used herein shall include the corresponding masculine, feminine or neuter forms,
and the singular form of names and pronouns shall include the plural and vice
versa.

      3.10 Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF CALIFORNIA WITHOUT GIVING EFFECT TO THE
PRINCIPLES OF CONFLICTS OF LAW.

      3.11 Submission to Jurisdiction. The parties hereto hereby irrevocably and
unconditionally consent to submit to the exclusive jurisdiction of the courts of
the State of California and of the United States of America, in each case
located in the County of San Diego, for any action or proceeding arising out of
or relating to this Agreement and the transactions contemplated hereby (and
agree not to commence any litigation relating hereto except in such courts), and
further agree that service of any process, summons, notice or document by U.S.
registered mail to its respective address shall be effective service of process
for any action or proceeding brought against it in any such court. The parties
hereto hereby irrevocably and unconditionally (a) waive any objection to the
laying of venue of any action or


                                       12
<PAGE>
proceeding arising out of this Agreement or the transactions contemplated hereby
in the courts of the State of California or the United States of America, in
each case located in the County of San Diego, and (b) waive and agree not to
plead or claim in any such court that any such action or proceeding brought in
any such court has been brought in an inconvenient forum.

      3.12 Waiver of Jury Trial. STRATAGENE AND THE SORGE ENTITIES HEREBY WAIVE
ANY RIGHT THEY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY ACTION OR
PROCEEDING DIRECTLY OR INDIRECTLY ARISING OUT OF, UNDER OR IN CONNECTION WITH
THIS AGREEMENT.

      3.13 Counterparts. This Agreement may be executed in any number of
counterparts, and each such counterpart hereof shall be deemed to be an original
instrument, but all such counterparts together shall constitute but one
agreement.

      3.14 Severability. Whenever possible, each provision of this Agreement
shall be interpreted in such manner as to be effective and valid, but if any
provision of this Agreement is held to be invalid or unenforceable in any
respect, such invalidity or unenforceability shall not render invalid or
unenforceable any other provision of this Agreement.

      3.15 Further Assurances. At any time or from time to time after the date
of this Agreement, Stratagene, on the one hand, and Sorge, on the other hand,
agree to cooperate with each other, and at the request of the other party, to
execute and deliver any further instruments or documents and to take all such
further action as the other party may reasonably request in order to evidence or
effectuate the consummation of the transactions contemplated hereby and to
otherwise carry out the intent of the parties hereunder.

      3.16 Entire Agreement; Effectiveness. This Agreement and the Merger
Agreement contain the entire agreement between the parties with respect to the
subject matter hereof and supersede all prior and contemporaneous arrangements
or understandings with respect thereto.

                            [Signature Page Follows]


                                       13
<PAGE>
            IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be executed by their respective officers thereunto duly authorized as of the day
and year first above written.


                                         STRATAGENE:


                                         STRATAGENE CORPORATION,
                                         a Delaware corporation


                                         By: /s/ RONNI L. SHERMAN
                                             -----------------------------------
                                                 Ronni L. Sherman
                                                 Executive Vice President and
                                                 General Counsel


                                         SORGE ENTITIES:


                                         JOSEPH A. SORGE


                                         By: /s/ JOSEPH A. SORGE
                                             -----------------------------------
                                                 Joseph A. Sorge


                                         J. A. SORGE TRUST I


                                         By: /s/ JOSEPH A. SORGE
                                             -----------------------------------
                                                 Joseph A. Sorge, Trustee


                                         J. A. SORGE TRUST II


                                         By: /s/ JOSEPH A. SORGE
                                             -----------------------------------
                                                 Joseph A. Sorge, Trustee

                [SIGNATURE PAGE TO REGISTRATION RIGHTS AGREEMENT]
<PAGE>
                                         J. A. SORGE TRUST III


                                         By: /s/ JOSEPH A. SORGE
                                             -----------------------------------
                                                 Joseph A. Sorge, Trustee


                                         J. A. SORGE TRUST IV


                                         By: /s/ JOSEPH A. SORGE
                                             -----------------------------------
                                                 Joseph A. Sorge, Trustee


                                         THE JOSEPH A. SORGE CHARITABLE
                                         REMAINDER TRUST DATED 12/26/02


                                         By: /s/ JOSEPH A. SORGE
                                             -----------------------------------
                                                 Joseph A. Sorge, Trustee


                                         BIOSENSE PARTNERS, L.P.


                                         By:   BIOSENSE MANAGEMENT, L.L.C.
                                         Its:  General Partner


                                               By: /s/ JOSEPH A. SORGE
                                                   -----------------------------
                                                       Joseph A. Sorge
                                                       Manager

                [SIGNATURE PAGE TO REGISTRATION RIGHTS AGREEMENT]