<PAGE>   1

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D. C. 20549

                                    FORM 10-Q

               QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF
                      THE SECURITIES EXCHANGE ACT OF 1934.

                  For the quarterly period ended March 31, 1998

                        Commission file number 000-21215

                                PROGENITOR, INC.
             (Exact name of registrant as specified in its charter)

                 DELAWARE                                   31-1344193
       (State or other jurisdiction                      (I.R.S. employer
     of incorporation or organization)                identification number)

                              4040 CAMPBELL AVENUE
                              MENLO PARK, CA 94025
                                 (650) 617-0880
               (Address, including zip code, and telephone number,
        including area code, of registrant's principal executive offices)

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. Yes [X] No [ ]

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date:

                       CLASS                   OUTSTANDING AT APRIL 30, 1998
           -----------------------------       -----------------------------
           Common Stock, $.001 par value          13,731,624 shares



<PAGE>   2



                                PROGENITOR, INC.

                                      INDEX
<TABLE>
<CAPTION>

                                                                    PAGE
                                                                    ----
PART I.  FINANCIAL INFORMATION
<S>                                                                <C>
Item 1.  Financial Statements (unaudited)

         Condensed Consolidated Balance Sheets -
           March 31, 1998 and September 30, 1997                      3

         Condensed Consolidated Statements of Operations -
           Three and six month periods ended March 31, 1998 and
           March 31, 1997, and May 8, 1992 (Date of Inception) to     4
           March 31, 1998

         Condensed Consolidated Statements of Cash Flows Six month
           periods ended March 31, 1998 and March 31, 1997 and
           May 8, 1992 (Date of Inception) to March 31, 1998          5

         Notes to the Unaudited Condensed Consolidated
           Financial Statements                                       6

Item 2.  Management's Discussion and Analysis of Financial
           Condition and Results of Operations                        7

PART II. OTHER INFORMATION                                           11

Item 1.  Legal Proceedings                                           11

Item 2.  Changes in Securities and Use of Proceeds                   11

Item 4.  Submission of Matters to a Vote of Security Holders         12

Item 6.  Exhibits and Reports on Form 8-K                            13

SIGNATURES                                                           14
</TABLE>


                                       2
<PAGE>   3

PART I.  FINANCIAL INFORMATION

ITEM I.  FINANCIAL STATEMENTS

                 PROGENITOR, INC. (A DEVELOPMENT STAGE COMPANY)

                     CONDENSED CONSOLIDATED BALANCE SHEETS
                                   (Unaudited)
--------------------------------------------------------------------------------
<TABLE>
<CAPTION>

                                  ASSETS
                                                           March 31,         September 30,
                                                            1998                 1997
                                                        ------------          ------------
<S>                                                     <C>                   <C>         
Current assets:
  Cash and cash equivalents                             $  9,465,000          $ 19,673,000
  Short-term investments                                   1,002,000                    --
  Accounts receivable                                        130,000               130,000
  Prepaid expenses and other current assets                  378,000               421,000
                                                        ------------          ------------
    Total current assets                                  10,975,000            20,224,000
                                                        ------------          ------------

Property and equipment, net                                2,419,000             1,919,000
Notes receivable-employees, net                              243,000               480,000
Intangible assets, net                                       807,000               962,000
                                                        ------------          ------------
    Total assets                                        $ 14,444,000          $ 23,585,000
                                                        ============          ============

      LIABILITIES AND STOCKHOLDERS' EQUITY

Current liabilities:
  Accounts payable                                      $    563,000          $  1,793,000
  Accrued liabilities                                      2,649,000             4,148,000
  Capital lease obligations, current                         809,000               762,000
                                                        ------------          ------------
    Total current liabilities                              4,021,000             6,703,000
                                                        ------------          ------------

Capital lease obligations, non-current                       637,000               942,000

Stockholder's equity:
  Preferred stock                                                 --                    --
  Common stock                                                14,000                13,000
  Stock subscription promissory note receivable             (500,000)           (1,000,000)
  Additional paid-in-capital                              79,893,000            79,651,000
  Deficit accumulated during development stage           (69,621,000)          (62,724,000)
                                                        ------------          ------------
    Total stockholders' equity                             9,786,000            15,940,000
                                                        ------------          ------------
    Total liabilities and stockholders' equity          $ 14,444,000          $ 23,585,000
                                                        ============          ============
</TABLE>


The accompanying notes are an integral part of the condensed consolidated
financial statements.


                                       3
<PAGE>   4

                 PROGENITOR, INC. (A DEVELOPMENT STAGE COMPANY)

                CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
                                   (Unaudited)
--------------------------------------------------------------------------------
<TABLE>
<CAPTION>

                                                                                                           
                                          THREE MONTHS ENDED                      SIX MONTHS ENDED              MAY 8, 1992  
                                                MARCH 31,                            MARCH 31,                   (DATE OF    
                                       ------------------------------      -----------------------------       INCEPTION) TO
                                            1998             1997              1998             1997           MARCH 31,1998
                                       ------------      ------------      ------------      ------------      ------------
<S>                                    <C>               <C>               <C>               <C>               <C>         
Revenues                               $    130,000      $    184,000      $    259,000      $    859,000      $  5,555,000

Operating expenses:
  Research and development                2,859,000         1,084,000         5,520,000         2,150,000        27,088,000
  Write-off of acquired in-process
    research and development                                                                                     21,092,000
  General and administrative                979,000           782,000         1,943,000         1,226,000        10,611,000
  Nonrecurring expenses                                                                                           1,506,000
                                       ------------      ------------      ------------      ------------      ------------
    Total operating expenses              3,838,000         1,866,000         7,463,000         3,376,000        60,297,000
                                       ------------      ------------      ------------      ------------      ------------

Loss from operations                     (3,708,000)       (1,682,000)       (7,204,000)       (2,517,000)      (54,742,000)

Nonrecurring expense                                                                                               (974,000)
Interest and other income                   168,000                             401,000                             657,000
Interest expense - related party                             (154,000)                           (265,000)       (1,940,000)
Interest expense - other                    (45,000)          (13,000)          (94,000)          (22,000)         (338,000)
                                       ------------      ------------      ------------      ------------      ------------
      Net loss                         $ (3,585,000)     $ (1,849,000)     $ (6,897,000)     $ (2,804,000)     $(57,337,000)
                                       ============      ============      ============      ============      ============

Net loss per common share:
    Basic and diluted                  $      (0.26)     $      (0.64)     $      (0.51)     $      (0.97)
                                       ============      ============      ============      ============
Shares used in computing
Net loss per common share:
    Basic and diluted                    13,613,338         2,886,550        13,511,964         2,886,227
                                       ============      ============      ============      ============
</TABLE>


The accompanying notes are an integral part of the condensed consolidated
financial statements.

                                       4

<PAGE>   5

                 PROGENITOR, INC. (A DEVELOPMENT STAGE COMPANY)

                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (Unaudited)
--------------------------------------------------------------------------------
<TABLE>
<CAPTION>

                                                                                                
                                                              SIX MONTHS ENDED                MAY 8, 1992
                                                                 MARCH 31,                      (DATE OF
                                                       --------------------------------       INCEPTION) TO 
                                                           1998                1997           MARCH 31, 1998
                                                       ------------        ------------        ------------
<S>                                                         <C>              <C>               <C>          
Cash flows from operating activities:
Net loss                                               $ (6,897,000)       $ (2,804,000)       $(57,337,000)
Adjustments to reconcile net loss to net cash
  used in operating activities:
  Depreciation and amortization                             681,000             147,000           2,550,000
  Gain on sale of equipment                                      --                  --             (23,000)
  Noncash expense for anti-dilution
    stock issuances                                              --                  --             763,000
  Write-off of acquired in-process
    research and development                                     --                  --          21,092,000
  Changes in operating assets and liabilities:
    Accounts receivable                                          --                  --            (130,000)
    Prepaid expenses and other current assets                43,000              25,000            (128,000)
    Notes receivable-employees, net                         237,000               1,000            (174,000)
    Accounts payable                                     (1,230,000)            186,000          (2,052,000)
    Accrued liabilities                                  (1,499,000)           (292,000)            938,000
    Accrued interest-related party                               --             265,000           1,912,000
                                                       ------------        ------------        ------------
    Cash used in operating activities                    (8,665,000)         (2,472,000)        (32,589,000)
                                                       ------------        ------------        ------------

Cash flows from investing activities:
  Purchases of property and equipment                    (1,026,000)           (570,000)         (3,436,000)
  Proceeds from sale of equipment                                --                  --              54,000
  Purchases of short-term investments                    (1,002,000)                 --          (1,002,000)
  Advances under convertible bridge
    promissory note                                              --          (1,308,000)         (3,770,000)
  Cash paid in purchase of Mercator                              --                  --            (763,000)
                                                       ------------        ------------        ------------
    Cash used in investing activities                    (2,028,000)         (1,878,000)         (8,917,000)
                                                       ------------        ------------        ------------

Cash flows from financing activities:
  Proceeds from note payable-related party                       --           2,889,000          20,555,000
  Proceeds from convertible debenture-related
    party                                                        --                  --             437,000
  Proceeds from bridge loan-related party                        --           1,308,000           3,665,000
  Deferred offering and acquisition costs                        --            (276,000)                 --
  Proceeds from issuance of stock, net                      243,000               6,000          25,238,000
  Proceeds from payments received on stock
    subscription note                                       500,000                  --             500,000
  Proceeds from capital lease financings                         --             550,000           1,694,000
  Principal payments on capital lease financings           (258,000)           (141,000)         (1,118,000)
                                                       ------------        ------------        ------------
    Cash provided by financing activities                   485,000           4,336,000          50,971,000
                                                       ------------        ------------        ------------

Net increase (decrease) in cash and cash
  equivalents                                           (10,208,000)            (14,000)          9,465,000
Cash and cash equivalents, beginning of period           19,673,000              22,000                  --

                                                       ------------        ------------        ------------
Cash and cash equivalents, end of period               $  9,465,000        $      8,000        $  9,465,000
                                                       ============        ============        ============
</TABLE>

The accompanying notes are an integral part of the condensed consolidated
financial statements.


                                       5
<PAGE>   6

                 PROGENITOR, INC. (A DEVELOPMENT STAGE COMPANY)

       NOTES TO THE CONDENSED UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


1. Basis of Presentation

        The unaudited condensed consolidated financial statements included
herein have been prepared by Progenitor, Inc. (the "Company") in accordance with
generally accepted accounting principles for interim information and pursuant to
the rules and regulations of the Securities and Exchange Commission. In the
opinion of management, the accompanying unaudited condensed consolidated
financial statements include all adjustments (consisting only of normal
recurring adjustments) necessary to present fairly the financial position,
results of operations and cash flows of the Company. The condensed consolidated
financial statements included herein should be read in conjunction with the
audited consolidated financial statements and the notes thereto included in the
Company's Form 10-K for the fiscal year ended September 30, 1997. Results for
the interim period are not necessarily indicative of the results for any other
interim period or for the full fiscal year.

2.       Short-Term Investments

        The Company has classified its short-term investments as
available-for-sale. Such investments are recorded at fair value and unrealized
gains and losses, when material, are reported as a separate component of
stockholders' equity. Realized gains and losses on sales of such securities are
reported in earnings and computed using the specific identification method.

3.      Net Loss per Share

        Effective December 31, 1997, the Company adopted Financial Accounting
Standards Board No. 128 "Earnings Per Share" (EPS) and, accordingly, all prior
periods have been restated. Basic EPS is computed as net income (loss) divided
by the weighted average number of common shares outstanding for the period.
Stock options to purchase 2,462,089 and 620,925 shares of common stock at prices
ranging from $0.20 to $4.375 and from $0.20 to $5.50 were outstanding at March
31, 1998 and 1997, respectively, and were not included in the calculation of
earnings per share as their effect was anti-dilutive. Additionally, at March 31,
1997, 2,369,496 shares of convertible preferred stock, representing 3,074,767
shares of common stock on an as-converted basis, were excluded from the
calculation of earnings per share as their effect was anti-dilutive.

4.      Stock Subscription Promissory Note Receivable

        In December 1997, Amgen Inc. paid $500,000 of the outstanding balance of
its stock subscription promissory note receivable by the Company, in accordance
with the terms of the note. The remainder of the note is scheduled to be repaid
in December 1998.

5.       Subsequent Events

        On May 13, 1998, the Company entered into two agreements with
Transamerica Business Credit ("Transamerica"). The first agreement relates to an
equipment lease line of $1.2 million, through which the Company has received
$829,000 in a sale-leaseback transaction. Under the second agreement, the
Company received $1.9 million, representing the total future license fees due
under an agreement which called for license fees to be paid over six years. The
Company has pledged these guaranteed payments as collateral for the loan along
with certain other personal and intellectual property. The note carries an
interest rate of 14.75% per year. In conjunction with the agreement, the Company
issued Transamerica a warrant to purchase 108,571 shares of common stock at a
strike price of $1.75 per share. The warrant expires 7 years from the
transaction date.


                                       6
<PAGE>   7

                 PROGENITOR, INC. (A DEVELOPMENT STAGE COMPANY)

ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
         OF OPERATIONS
--------------------------------------------------------------------------------



   The following discussion is intended to assist in the understanding and
assessment of significant changes and trends related to the results of
operations and financial condition of Progenitor, Inc., ("Progenitor" or the
"Company"). This discussion and analysis should be read in conjunction with the
Company's Unaudited Condensed Consolidated Financial Statements and Notes
thereto included herein, and with the Consolidated Financial Statements and
Notes thereto included in the Company's Form 10-K for the fiscal year ended
September 30, 1997.

        In addition to historical information, the following management's
discussion and analysis includes certain forward-looking statements regarding
events and financial trends which may affect the Company's future operating
results and financial position. These forward-looking statements include but are
not limited to statements regarding: future sources of revenue; uncertainty of
product development; uncertainty of additional funding; and liquidity and
capital resources. Readers are cautioned not to place undue reliance on these
forward-looking statements, which speak only as of the date hereof. The Company
undertakes no obligation to publicly release the result of any revisions to
these forward-looking statements to reflect events or circumstances after the
date hereof or to reflect the occurrence of unanticipated events.

        The forward-looking statements included herein are also subject to a
number of other risks and uncertainties that could cause the Company's actual
results and financial position to differ materially from those anticipated in
the forward-looking statements. Such risks and uncertainties include, but are
not limited to: uncertainties relating to the technological approaches of the
Company; history of operating losses and anticipation of future losses;
uncertainty of product development; need for additional capital and uncertainty
of additional funding; dependence on collaborators and licensees; intense
competition and rapid technological change; uncertainty of patents and
proprietary rights; management of growth, and risks of acquiring new
technologies; uncertainties related to clinical trials; government regulation
and uncertainty of obtaining regulatory approval; dependence on key personnel;
dependence on research collaborators and scientific advisors; control of the
Company by, and potential conflicts of interest with, Interneuron; uncertainty
of health care reform measures and third-party reimbursement; risk of product
liability; no assurance of an active trading market and potential volatility of
trading prices; possible delisting from the Nasdaq National Market and market
illiquidity; redemption of Warrants; current prospectus required to exercise the
Warrants; anti-takeover considerations; hazardous and radioactive materials and
environmental matters; and the absence of dividends. Due to the foregoing
factors, it is possible that in some future period the Company's results of
operations may be below the expectations of public market analysts and
investors. These and other risks and uncertainties related to the Company's
business are described in detail in the Company's Form 10-K for the fiscal year
ended September 30, 1997 under the caption "Factors That May Affect Future
Financial Results."

OVERVIEW

        A development stage company, Progenitor was incorporated in February
1992 and commenced operations in May 1992. Progenitor has devoted substantially
all of its resources since inception to research and development programs. To
date, all of Progenitor's revenues have resulted from payments from
collaborators and licensees and a grant from the U.S. Department of Commerce's
National Institute of Standards and 

                                       7


<PAGE>   8

Technology Advanced Technology Program ("ATP") that was awarded to Progenitor in
November 1994. Royalties, payments from collaborators, license fees, payments
under governmental grants and investment income, in each case, if any, are
expected to be the only sources of revenue for the foreseeable future. Certain
payments under collaborative and license arrangements are contingent upon the
Company meeting certain milestones. Payments under collaborative or licensing
arrangements, if any, will be subject to significant fluctuation in both timing
and amount, and therefore the Company's results of operations for any period may
not be comparable to the results of operations for any other period. The Company
has not yet received any royalties or other revenues from the sale of products
or services and does not expect to receive significant revenues from sales of
products for the next several years, if at all. As of March 31, 1998, Progenitor
had total stockholders' equity of $9.8 million, including an accumulated deficit
of $69.6 million.

        Significant discovery, research and development efforts will be required
prior to the time any of the Company's gene discoveries may lead to product
candidates or result in products that may be brought to the market, if at all.
Products, if any, resulting from the Company's research and development programs
are not expected to be commercially available for a number of years, if at all,
even if any are successfully developed and proven safe and effective.
Significant additional research and development efforts and extensive
preclinical studies and clinical trials will be required prior to submission of
any regulatory application for commercial use.

RESULTS OF OPERATIONS

        The Company recognized ATP grant revenue of $130,000 and $259,000 in the
three and six month periods ended March 31, 1998 respectively. In the three and
six month periods ended March 31, 1997 revenue totaled $184,000 and $859,000,
respectively. Other than a $500,000 milestone payment from Chiron in the six
month period ended March 31, 1997, the revenues in the 1997 periods were derived
from the ATP grant. The Company's ATP grant is scheduled to expire in May 1998.

        Research and development ("R&D") expenses increased 164% to $2.9 million
in the quarter ended March 31, 1998 from $1.1 million in the quarter ended March
31, 1997. R&D expenses increased 157% to $5.5 million in the six month period
ended March 31, 1998 from $2.2 million in the comparable period in the prior
year. The increase is primarily the result of increased staffing and research
activity due to the acquisition of Mercator Genetics, Inc. ("Mercator"). The
Company expects R&D expenses in the remainder of fiscal 1998 to continue to
exceed 1997 levels as a result of the Mercator acquisition. Further increases in
R&D expenses in future periods based on the expansion or proliferation of
research programs will depend on the availability of capital.

        General and administrative ("G&A") expenses increased 25% to $979,000 in
the quarter ended March 31, 1998 from $782,000 in the quarter ended March 31,
1997. G&A expenses increased 58% to $1.9 million in the six month period ended
March 31, 1998 from $1.2 million in the comparable period in the prior year. The
increase is due to higher headcount resulting from the Mercator acquisition, as
well as incremental corporate expenses incurred as a result of operating as a
publicly held company. The Company expects G&A expenses to continue to increase
in the future, depending on the level of R&D spending.

        Related party interest expense of $154,000 and $265,000 in the three and
six month periods ended March 31, 1997, respectively, arose from a promissory
note owed Interneuron until the Company's IPO in August 1997. Other interest
expense increased to $45,000 and $94,000 in the three and six month periods
ended March 31, 1998, respectively, from $13,000 and $22,000 in the comparable
three and six month periods, respectively, in the prior year, due to the
Company's assumption of Mercator's capital lease obligations. During the three
and six month periods ended March 31, 1998 the Company recorded $168,000 

                                       8


<PAGE>   9

and $401,000, respectively, of interest and other income primarily from interest
earned on cash balances.


LIQUIDITY AND CAPITAL RESOURCES

        As of March 31, 1998, the Company had cash, cash equivalents and
short-term investments of $10.5 million, a decrease of $9.2 million in the six
month period ended March 31, 1998. The decrease was primarily due to the net
loss of $6.9 million and a $2.7 million decrease in accrued liabilities and
accounts payable. The decrease in accrued liabilities and accounts payable
largely resulted from the payment of liabilities outstanding at the end of the
1997 fiscal year relating to the Mercator acquisition and the Company's initial
public offering (the "Offering"), both of which were completed in the fourth
quarter of fiscal 1997.

        The Company expects negative cash flow from operations to continue for
the foreseeable future. The Company will require substantial additional funds to
continue research and development, conduct preclinical studies and clinical
trials, conduct activities relating to commercialization of rights it has
retained in collaborative or license agreements, if any, and expand
administrative capabilities. The Company estimates that, at its planned rate of
spending, its existing cash and cash equivalents, together with the funds
received subsequent to March 31, 1998 (see note 6) will be sufficient to meet
its funding requirements at least through March 31, 1999. In order to achieve
this result, however, the Company will need to closely manage the rate of
expenditures for all of its research programs. Although the Company anticipates
that its existing cash balances will be sufficient to meet its funding
requirements for its primary research programs for at least the next twelve
months, the Company may be required to curtail the expansion of, or to reduce
the level of expenditures for, certain of its other research programs, in the
future or to seek corporate collaborations with respect to such programs at an
earlier stage than would be required if the Company had greater financial
resources or to obtain other funding. There can be no assurance that any such
corporate collaboration will be obtained on terms favorable to the Company or at
all or that any such funding will be available on terms favorable to the Company
or at all. In addition, there can be no assurance that the Company's assumptions
regarding its future levels of expenditures and operating losses will prove
accurate.

        The Company's future funding requirements will depend on many factors,
including any expansion or acceleration of the Company's research and
development programs; the results of research and development, preclinical
studies and clinical trials conducted by the Company or its collaborative
partners or licensees, if any; the acquisition and licensing of products and
technologies or businesses, if any; the Company's ability to establish and
maintain corporate relationships and academic collaborations; the Company's
ability to manage growth; competing technological and market developments; the
time and costs involved in filing, prosecuting, defending and enforcing patent
and intellectual property claims; the receipt of licensing or milestone fees
from any current or future collaborative and licensing arrangements, if
established; the continued funding of governmental research grants; the timing
of regulatory approvals, if any; and other factors. To the extent undertaken by
the Company, the time and costs involved in conducting preclinical studies and
clinical trials, seeking regulatory approvals, and scaling-up manufacturing and
commercialization activities also would increase the Company's funding
requirements.

        The Company will need to raise substantial additional capital to fund
operations. The Company intends to seek additional funding through public or
private equity or debt financing and collaborative arrangements. There can be no
assurance that additional financing will be available when needed, or that, if
available, such financing will be available on terms acceptable to the Company.
If additional funds are raised by issuing equity securities, dilution to
existing stockholders will result. In addition, in the event that additional
funds are obtained through collaborative or license arrangements, 


                                       9


<PAGE>   10

such arrangements may require the Company to relinquish rights to certain of its
technologies or potential products that it would otherwise seek to develop or
commercialize itself.

IMPACT OF THE YEAR 2000 ISSUE

        The Company has begun the process of evaluating the impact of the Year
2000 problem and expects to complete such evaluation during fiscal 1998. The
Year 2000 problem is the result of computer programs being written using two
digits rather than four to define the applicable year. Any programs that have
time-sensitive software may recognize a date using "00" as the year 1900 rather
than the year 2000. This could result in a major system failure or
miscalculations. The Company cannot quantify the potential costs associated with
the Year 2000 problem at this time. Although the Company does not currently
expect that the impact of this computer program flaw will be material, there can
be no assurance that the Company will not discover Year 2000 problems with
respect to the Company's computer systems in the course of its evaluation
process that would have a material adverse effect on the business, financial
condition or results of operations of the Company. In addition, the Year 2000
problem may impact other entities with which the Company transacts business, and
there can be no assurance that such impact will not have a material adverse
effect on the business, financial condition or results of operations of the
Company.


                                       10
<PAGE>   11



PART II.  OTHER INFORMATION
--------------------------------------------------------------------------------


Item 1.  LEGAL PROCEEDINGS

         The Company is not currently a party to any litigation that could have
a material adverse effect on its business, financial condition or results of
operations. However, from time to time the Company may be threatened with, or
named as a defendant in, lawsuits, including administrative claims and lawsuits
brought by employees or former employees.

Item 2. CHANGES IN SECURITIES AND USE OF PROCEEDS

        (d) Use of Proceeds

        As described above in "Management's Discussion and Analysis of Financial
Condition and Results of Operations," the Company has completed the Offering.
The following information relates to the use of proceeds of the Offering:

        (1) Effective Date of Registration Statement and Commission File Number.
The Company's Registration Statement on Form S-1, File No. 333-05369 (the
"Registration Statement"), relating to the Offering, became effective on August
6, 1997.

        (2) Offering Date. The initial closing date of the Offering was August
12, 1997. A subsequent closing in connection with the partial exercise by the
Underwriters of the Offering of their over-allotment option occurred on
September 10, 1997.

        (3) Managing Underwriters.  Lehman Brothers Inc.

        (4) Securities Registered and Proposed Aggregate Offering Price. The
Company registered a total of 3,162,500 Units, each Unit consisting of one share
of Common Stock ("Unit Share") and one Warrant, and 3,162,500 shares of Common
Stock issuable upon exercise of the Warrants (the "Warrant Shares"). The
proposed maximum aggregate offering price was $37,950,000 for the Units and
$56,925,000 for the Warrant Shares.

        (5) Securities Sold. A total of 2,875,000 Units were sold pursuant to
the Offering. This consisted of 2,750,000 Units sold on August 12, 1997 upon the
initial closing of the Offering, and 125,000 Units sold on September 10, 1997
pursuant to the partial exercise, at the request of Lehman Brothers Inc. as
managing underwriter, of the over-allotment option granted to the Underwriters.
None of the Warrants had been exercised as of February 9, 1998, and consequently
no Warrant Shares had been sold. The Company intends to maintain the
effectiveness of the Registration Statement to the extent required by the terms
of the Warrants with respect to the 2,875,000 Warrant Shares issuable upon
exercise of the Warrants actually sold.

        (6) Aggregate Gross Proceeds, Expenses and Aggregate Net Proceeds. The
sale of the 2,875,000 Units generated aggregate gross proceeds of $20,125,000,
consisting of $15,453,125 from the sale of the Unit Shares (at a price of $5.375
per share) and $4,671,875 from the sale of the Warrants (at a price of $1.625
per Warrant). The aggregate net proceeds to the Company from the sale of the
2,875,000 Units were approximately $17,200,000, after deducting underwriting
discounts and commissions of approximately $1,200,000 and estimated expenses of
the Offering of approximately $1,700,000 payable by the Company. The Company
also received $4,500,000 in cash and a $1,000,000 promissory note from the sale
of the Amgen Shares ($500,000 of which was repaid by Amgen in December 1997),
and approximately $67,000 in cash from the sale of 25,000 shares of Common Stock
to The Ohio University Foundation, pursuant to a stock purchase right.


                                       11

<PAGE>   12

        (7) Use of Proceeds. Through March 31, 1998, the Company used $6,757,000
of the net proceeds of the Offering, together with the cash proceeds received
from the sale of the Amgen Shares and the sale of 25,000 shares of Common Stock
to The Ohio University Foundation, for research and development and $2,308,000
of such proceeds for administration. In addition, the Company used a portion of
such net proceeds as follows: (i) approximately $579,000 to pay expenses
relating to employee benefit and retention plans relating to the Acquisition;
(ii) approximately $2,776,000 legal, accounting and other costs incurred in the
Acquisition and related Form S-4 registration statement; (iii) approximately
$354,000 to facilitate employee relocation, to Mercator's facility in
California; (iv) approximately $389,000 for other costs such as benefit costs,
the consolidation of operations, the elimination of duplicate systems and
facilities, and other integration costs; and (v) approximately $1,026,000 for
purchases of property and equipment. The Company anticipates using the balance
of such net proceeds primarily for research and development, and also for the
expansion or upgrade of facilities for the acquisition of equipment and for
working capital and other general corporate purposes. The Company also may use
such proceeds for other purposes, including the acquisition of technology
rights, products, equipment, businesses or assets of other companies. At March
31, 1998, the Company had approximately $8,810,000 of such proceeds remaining,
held in cash and cash equivalents.

        The amounts actually expended for each purpose, including the allocation
of funding among the Company's research programs, will depend on numerous
factors, including any expansion or acceleration and the breadth of the
Company's research and development programs; the results of research and
development, preclinical studies and clinical trials conducted by the Company or
its collaborative partners or licensees, if any; the acquisition and licensing
of products and technologies or businesses, if any; the Company's ability to
establish and maintain corporate relationships and academic collaborations; the
Company's ability to manage growth; competing technological and market
developments; the time and costs involved in filing, prosecuting, defending and
enforcing patent and intellectual property claims; the receipt of licensing or
milestone fees from any current or future collaborative and license
arrangements, if established; the continued funding of governmental research
grants; the timing of regulatory approvals; and other factors.

Item 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

        The Company's Annual Meeting of Stockholders was held on March 10, 1998
(the "Annual Meeting"). At the Annual Meeting, stockholders voted on two
matters: (i) the election of eight directors to serve until the next Annual
Meeting and (ii) the ratification of appointment of Coopers & Lybrand L.L.P. as
the Company's independent auditors. The stockholders elected management's
nominees for director and ratified the appointment of independent auditors by
the following votes, respectively:

(i)      Election of directors:
<TABLE>
<CAPTION>

                                           VOTES FOR       VOTES AGAINST
                                           ---------       -------------
<S>                                        <C>                  <C>   
Douglass B. Given, M.D., Ph.D.             7,532,386            26,121
Glenn L. Cooper, M.D.                      7,535,727            22,780
Robert P. Axline                           7,321,727           236,780
Alexander M. Haig, Jr.                     7,321,727           236,780
Morris Laster, M.D.                        7,535,727            22,780
Robert R. Momsen                           7,535,727            22,780
Jerry P. Peppers                           7,535,727            22,780
David B. Sharrock                          7,535,727            22,780
</TABLE>

                                       12

<PAGE>   13




(ii) Ratification of appointment of Coopers & Lybrand L.L.P. as independent
auditors:

       VOTES FOR             VOTES AGAINST            VOTES ABSTAINED
       ---------             -------------            ---------------
       7,511,518                  910                     46,079


Item 6.  EXHIBITS AND REPORTS ON FORM 8-K

      (a)      Exhibits

               EXHIBIT INDEX

               Exhibit No.    Description

               27.1           Financial Data Schedule


        (b)    Reports on Form 8-K

               None.

                                       13
<PAGE>   14



                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                                      PROGENITOR, INC.

    May 15, 1998                                      /s/ Mark N.K. Bagnall
  ---------------                                     --------------------------
        Date                                          Mark N.K. Bagnall
                                                      Vice President, Finance
                                                          and Chief Financial
                                                          Officer



                                       14







<PAGE>   15



                                  EXHIBIT INDEX

               Exhibit No.         Description

                      27.1         Financial Data Schedule







                                       16