Exhibit 99.1:

CORPORATE PRESS RELEASE                         LOGO: CHARLES RIVER LABORATORIES

Dennis R. Shaughnessy
Investor Relations
978-658-6000 Ext. 1329
www.criver.com

                CHARLES RIVER COMPLETES ACQUISITION OF PRIMEDICA

         WILMINGTON, MA.; FEBRUARY 27, 2001: Charles River Laboratories
International, Inc. (NYSE:CRL), through its wholly-owned subsidiary Charles
River Laboratories, Inc., today announced the completion of the acquisition of
Primedica Corporation from Genzyme Transgenics Corporation (NASDAQ: GZTC).
Primedica, headquartered in Worcester, MA is a leading provider of pre-clinical
drug discovery and development services to the biopharmaceutical industry. The
acquisition is expected to be accretive to Charles River's earnings in 2001 by
$0.03 per share. The signing of a definitive agreement to purchase Primedica was
announced on February 7.

         The purchase price paid by Charles River for Primedica was $51.9
million, including $26 million in cash, $16.5 million in restricted stock, and
$9.4 million in assumed liabilities. Primedica's revenues increased 31% in 2000
to $72.3 million. EBITDA (earnings before interest, taxes, depreciation and
amortization) in 2000 was $6.5 million, an increase of more than 250% over the
prior year. For the last six months of 2000, Primedica's revenues and EBITDA
were $39.9 million and $4.4 million, respectively, evidencing substantial
revenue growth and improving profitability. Charles River expects to achieve
significant additional cost savings as well as revenue synergies.

         Primedica will be integrated into Charles River's biomedical products
and services segment. Primedica's service offerings include drug efficacy and
safety testing, where Charles River already offers a number of value-added
services, and biopharmaceutical production, drug formulation and bioanalytical
chemistry, where Charles River does not currently have significant capabilities.

         Charles River Laboratories, based in Wilmington, MA, is a leading
provider of critical research tools and integrated support services that enable
innovative and efficient drug discovery and development. The Company is the
global leader in providing the animal research models required in research and
development for new drugs, devices and therapies. The Company also offers a
broad and growing portfolio of biomedical products and services that enable
customers to reduce cost, increase speed, and enhance productivity and
effectiveness in drug discovery and development. Charles River's customer base
spans over 50 countries, and includes all of the major pharmaceutical and
biotechnology companies, as well as many leading hospitals and academic
institutions. The Company operates 70 facilities in 15 countries worldwide.
Additional information is available on the Charles River web site,
http://www.criver.com.

         This document may contain forward looking statements. Such statements
involve a number of risks and uncertainties that could cause actual results to
differ materially from those stated or implied by the forward looking
statements, including the failure to recognize cost savings and expected
synergies and revenue growth in connection with the acquisition, acquisition
integration risks, industry trends including outsourcing in pre-clinical drug
discovery and development, new displacement technologies, USDA and FDA
regulation, changes in law, special interest groups, continued availability of
products and suppliers, biosecurity contaminations, retention of key personnel,
and others that are described in Risk Factors contained in the Company's SEC
filings, including its most recent Registration Statement filed on Form S-3
dated February 23, 2001. The Company disclaims an intent or any obligation to
update forward looking statements, and otherwise claims the "safe harbor"
protections for forward looking statements afforded under The Private Securities
Litigation Reform Act of 1995.