CERTIFICATE OF INCORPORATION

                                       of

                                CPF/METPATH INC.




FIRST, the name of the Corporation is

                                CPF/MetPath Inc.

SECOND,  the  address  of the  corporation's  registered  office in the State of
Delaware is 1209 Orange Street, in the City of Wilmington, County of New Castle.
The  name of the  Registered  Agent at such  address  is The  Corporation  Trust
Company.

THIRD,  the  purpose  of the  corporation  is (i) to own  and  operate  medical,
clinical,   industrial  and  research   laboratories,   and  (ii)  to  research,
manufacture, design, construct, use, buy, sell, lease, hire and deal in and with
articles and property of all kinds, to render  services of all kinds,  and (iii)
generally to engage in any lawful act or activity for which  corporations may be
organized under the General Corporation Law of Delaware.

FOURTH, the total number of shares of all classes of stock which the corporation
shall have  authority to issue is 1,000 shares which shall be Common Stock,  all
of which shares shall be without par value, and each with a right to one vote.

                                        1



FIFTH, the name and mailing address of the Incorporator is as follows:

        Name                                         Mailing Address

        Raymond C. Marier                            2 West Market Street
                                                     Corning, NY 14830


SIXTH,  the names  and  mailing  addresses  of the  persons  who are to serve as
directors  until the first annual meeting of  stockholders of the corporation or
until their successors axe elected and qualify, are as follows:

        Name                                          Mailing Address

        Raymond C. Marier                             2 West Market Street
                                                      Corning, NY  14830

        Richard A. Michaelson                         One Malcolm Avenue
                                                      Teterboro, NJ  07608

        Douglas M. VanOort                            2 West Market Street
                                                      Corning, NY  14830


SEVENTH,  the  corporation  may  indemnify,  to the  full  extent  permitted  by
applicable  law, any person who was or is a party, or is threatened to he made a
party, to any threatened or pending action,  suit or proceeding,  whether civil,
criminal, administrative, or investigative, by reason of the fact that he or she
is or was a director or officer of the corporation,  or is or was serving at the
request of the  corporation,  as a director  or officer of another  corporation,
partnership,  joint  venture,  trust or other  enterprise.  Any  indemnification
pursuant to the foregoing shall be made by the corporation only as authorized in
the specific case upon a determination  that  indemnification of the director or
officer is proper under the circumstances

                                        2



because he or she has met any  legally  applicable  standard  of  conduct.  Such
determination may be made (i) be resolution of the Board of Directors adopted in
the  manner  provided  in the  By-laws of the  corporation,  or (ii) if a quorum
consisting of directors or are not parties to such action,  suit or  proceeding,
is not obtainable,  or, even if obtainable,  a quorum of disinterested directors
so directs,  by independent legal counsel in a written opinion,  or (iii) by the
stockholders.

EIGHTH,  any action  required or  permitted to be taken at any annual or special
meeting  of  stockholders  of the  corporation  may be taken  without a meeting,
without prior notice and without a vote, if a consent in writing,  setting forth
the actions so taken, shall be signed by the holders of outstanding stock having
not less than the minimum  number of votes that would be  necessary to authorize
or take such action at a meeting at which all shares  entitled  to vote  thereon
are present and voted.

     THE UNDERSIGNED, being the sole Incorporator hereinbefore named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, does hereby make this Certificate, declaring and certifying
that this is his act and

                                        3



deed and the facts herein stated are true, and  accordingly has hereunto set his
hand this 14th day of October, 1991.



                                          /s/ Raymond C. Marier
                                          --------------------------------
                                                     Raymond C. Marier
                                                     2 West Market Street
                                                     Corning, NY 14830


STATE OF NEW YORK  )
                   )  s.s.:
COUNTY OF STEUBEN  )


     BE IT REMEMBERED, that on this 14th day of October, 1991, personally came
before me, a Notary Public in and for the State of New York and the County of
Steuben, Raymond C. Marier, the sole Incorporator named in the foregoing
Certificate of Incorporation, known to me personally to be such, and he
acknowledged the said Certificate to be his act and deed and that the facts
stated therein are truly set forth.



                          GIVEN  under  my  hand  and  seal of
                          office the day and year aforesaid.



                                      /s/ Barbara E. Wellington
                          -------------------------------------
                                      Barbara E. Wellington

                                        4



                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                                CPF/METPATH INC.


The  undersigned  directors of  CPF/MetPath  Inc., a Delaware  Corporation  (the
"Corporation"), for purposes of amending the Certificate of Incorporation of the
Corporation filed October 16, 1991, hereby certify as follows:

FIRST,  the Certificate of Incorporation is hereby amended such that name of the
Corporation is changed to CPF/Corning Inc.

SECOND, the Corporation has not received any payment for any of its stock.

THIRD,  the  amendment  herein  has been duly  adopted  in  accordance  with the
provisions  of  Section  241 of the  General  Corporation  Law of the  State  of
Delaware to be effective as

                                        5



provided  therein,  and this  Certificate  is duly executed by a majority of the
directors of the  Corporation in accordance with Section  103(a)(2)(ii)  of said
General Corporation Law.


                                               /s/ Raymond C. Marier
                                               ----------------------
                                               Raymond C. Marier
                                               2 West Market Street
                                               Corning, NY  14830
                                               [Director]


                                               /s/ Douglas M. VanOort
                                               ----------------------
                                               Douglas M. VanOort
                                               2 West Market Street
                                               Corning, NY  14830
                                               [Director]


STATE OF NEW YORK )
                  ) S.S.:
COUNTY OF STEUBEN )


Be it remembered  that on this 4th day of November,  1991 personally came before
me a Notary  Public  in and for the  State of New York and  County  of  Steuben,
Raymond C. Marier and Douglas M. VanOort named in the foregoing  Certificate  of
Amendment,  known to me personally to be such,  and they each  acknowledged  the
said  Certificate  to be his act and deed and that the facts stated  therein are
truly set forth.

                                Given  under  my  hand  and  seal of
                                office the day and year aforesaid.


                                       /s/ Barbara E. Wellington
                                ---------------------------------------------
                                       Barbara E. Wellington
                                       Notary Public, State of New York
                                       Qualified in Steuben County
                                       No. 4914239
                                       My Commission Expires December 14, 1991
CPF
a:\Amend.

                                        6



STATE OF DELAWARE                                              BK 1221 PG 0535
SECRETARY OF STATE
DIVISION OF CORPORTIONS
FILED 10:30 AM 11/26/1991
721330013 - 2276289

                              CERTIFICATE OF MERGER
                                       OF
                       CLINICAL PATHOLOGY FACILITY, INC.,
                           A PENNSYLVANIA CORPORATION
                                      INTO
                    CPF/CORNING INC., A DELAWARE CORPORATION



The undersigned corporation DOES HEREBY CERTIFY:

FIRST:   That the name and state of Incorporation of each of the constituents of
         the Merger is as follows:

                    NAME                                STATE OF INCORPORATION

         Clinical Pathology Facility, Inc.                     Pennsylvania
         CPF/Corning Inc.                                      Delaware

SECOND:  That an Agreement of Merger dated November 11, 1991 between CPF/Corning
         Inc., a Delaware corporation and Clinical Pathology Facility, Inc., a
         Pennsylvania corporation ("Clinical"), the constituent corporations of
         the merger, has been approved, adopted, certified, executed and
         acknowledged by each of the constituent corporations as follows: In the
         case of CPF/Corning Inc., in accordance with the requirements of
         Subsection (c) of Section 252 of the Delaware Corporation Law of the
         State of Delaware; and in the case of Clinical, in accordance with
         Section 1924 of the Associations Code of the Commonwealth of
         Pennsylvania.

THIRD:   That the name of the surviving corporations of the Merger is hereby
         changed from CPF/CORNING INC., a Delaware corporation, to CLINICAL
         PATHOLOGY FACILITY, INC., a Delaware corporation.

FOURTH:  That the Certificate of Incorporation of CPF/Corning Inc., a Delaware
         corporation, shall be the Certificate of Incorporation of the surviving
         corporation except that Article First of the Certificate of
         Incorporation shall be amended to read in full as follows:

         "FIRST, the name of the Corporation is Clinical Pathology Facility,
         Inc."

FIFTH:   That the executed Agreement and Plan of Merger is on file at the
         principal place of business of the surviving corporation, the address
         of which is 711 Bingham Street, Pittsburgh, Pennsylvania 15203.

                                        7



SIXTH:   That a copy of the executed Agreement and Plan of Merger will be
         furnished by the surviving corporation on request and without cost to
         any stockholder of either constituent corporation.

SEVENTH: That the authorized capital stock of each foreign [to Delaware]
         corporation which is a party to the merger is as follows:

                                                  Shares           Par
         Corporation                 Class      Authorized        Value

Clinical Pathology Facility, Inc.    Common       600,000      $1 per share
a Pennsylvania corporation

The undersigned officers of the surviving corporation of the merger do sign this
Certificate of Merger pursuant to Section 252(c) of the General  Corporation Law
of the State of Delaware.

November 26, 1991                     CPF/CORNING INC.


[SEAL]                                By:/s/     Richard A. Michaelson
                                         ----------------------------------
                                           Richard A. Michaelson, President



ATTEST:



/s/    Raymond C. Marier
- ----------------------------
Raymond C. Marier, Secretary


                                        8



                              CERTIFICATE OF MERGER

                                       OF

                        MEDICAL MANAGEMENT SYSTEMS, INC.

                                      INTO

                        CLINICAL PATHOLOGY FACILITY, INC.


                     Pursuant to Section 252 of the General
                    Corporation Law of the State of Delaware

                                     * * * *

                              The  undersigned   hereby  certifies that:

                               1.     The name of and state of incorporation of
each of the constituent corporations are as follows:

                     Name                              State of Incorporation

         MEDICAL MANAGEMENT SYSTEMS, INC.              Pennsylvania

         CLINICAL PATHOLOGY FACILITY, INC.             Delaware

         2. An Agreement and Plan of Merger dated as of December 6, 1994 (the
"Merger Agreement") between Medical Management Systems, Inc. and Clinical
Pathology Facility, Inc. has been approved, adopted, certified, executed and
acknowledged by each of the constituent corporations in accordance with the
requirements of Section 252(c) of the General Corporation Law of the State of
Delaware.

         3. The name of the surviving corporation is Clinical Pathology
Facility, Inc.

         4. The Certificate of Incorporation of Clinical Pathology Facility,
Inc. in effect at the effective time of the merger shall be the Certificate of
Incorporation of the surviving corporation except that Article 1 of the
Certificate of Incorporation of Clinical Pathology Facility, Inc shall be
amended as of the effective time of the Merger to read as follows:

              "The name of the Corporation is MetPath (PA) Inc."

         5. The surviving corporation is a corporation of the State of Delaware.

         6. The executed Merger Agreement is on file at the principal place of
business of the surviving corporation at 711 Bingham Street, Pittsburgh,
Pennsylvania 15213.

         7. A copy of the Merger Agreement will be furnished by the surviving
corporation, on request and without cost, to any stockholder of any constituent
corporation.


                                                         9



         8. The authorized capital stock of the Medical Management Systems, Inc.
is 2,000,000 shares of Common Stock, par value $1.00 per share.

         9. That the merger shall become effective at 11:59 P.M. on December 31,
1994.

            IN WITNESS WHEREOF, this Certificate of Merger has been executed on
this 6th day of December, 1994.


Attest:                               CLINICAL PATHOLOGY FACILITY, INC.

/s/ Leo C. Farrenkopf, Jr                     By: /s/ James D. Chambers
- -------------------------                         ------------------------
Leo C. Farrenkopf, Jr.                            James D. Chambers
Secretary                                         Vice President

                                       10



                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION


MetPath (PA) Inc. a corporation organized and existing under and by virtue of
the General Corporation Law of the state of Delaware,

         DOES HEREBY CERTIFY:

         FIRST: By unanimous written consent of the Board of Directors,
resolutions were duly adopted setting forth a proposed amendment of Article 1 of
the Certificate of Incorporation of said corporation declaring said amendment to
be advisable and calling a meeting of the stockholders of said corporation for
consideration thereof. The resolution setting forth the proposed amendment is as
follows:

         RESOLVED, that the Board of Directors hereby approves the amendment to
Article 1 of the Company's Certificate of Incorporation to read as follows:

         The name of the corporation (which is hereafter referred to as the
"Corporation") is Corning Clinical Laboratories of Pennsylvania Inc.

         SECOND: That said amendment was approved by the unanimous written
consent of the sole stockholder of the Corporation in accordance with Section
228 of the General Corporation Law of the state of Delaware.

         THIRD: That said amendment was duly adopted in accordance with Section
242 (a)(1) of the Business Corporation Act of the state of Delaware

         IN WITNESS WHEREOF, said corporation has used this certificate to be
signed by Raymond C. Marier, its Vice President, and Leo C. Farrenkopf, Jr., its
Secretary this 28th day of December, 1995.


                                             BY: /s/ Raymond C. Marier
                                                ---------------------------
                                                 Raymond C. Marier
                                                 Vice President
                                       
                                       
                                         ATTEST: /s/ Leo C. Farrenkopf, Jr.
                                                ---------------------------
                                             Leo C. Farrenkopf, Jr.
                                             Secretary
                                       
                                       11