This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kommineni, V. R. C. Articles by Vesselinovitch, S. D. Search for Related Content PubMed PubMed Citation Articles by Kommineni, V. R. C. Articles by Vesselinovitch, S. D.

The Significance of Perinatal Age Periods and the Dose of Urethan on the Tumor Profile in the MRC Rat¹

The Eppley Institute for Research in Cancer, University of Nebraska College of Medicine, Omaha, Nebraska 68105 [V. R. C. K., M. G.], and Department of Radiology, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois 60637 [N. M., S. D. V.]

The role of the prenatal, neonatal, and postweaning age periods in the carcinogenesis of various tissues of MRC rats was investigated by exposure to urethan. The animals were given either one injection (2 or 4 days prenatally) or six injections (postnatally) of specified solutions of urethan at 3-day intervals. The first urethan injections were given on the 1st, 28th, or 46th day of life.

The newborn rats developed tumors at specific sites in significantly higher incidence than the animals treated at other age periods. Rats which were exposed to urethan in utero developed liver tumors and Anitschkow cell sarcomas of the heart. Neonatally treated animals had gliomas of the brain, neurilemomas, and embryonal kidney tumors in addition to the latter two types of tumors. The urethan-treated weanlings showed no heart or brain neoplasms but did develop the other types of tumors with low frequency.

It was concluded that the neoplastic competence of the tissue at a given age governs the outcome of its carcinogenesis independently from its carcinogenic potential at other times and from the carcinogenesis in the other organs.

¹ Supported by Contract PH 43-68-959 from the USPHS; Training Grant CA05220-01 from the NIH; Grant 69-6 from the American Cancer Society, Illinois Division, Inc.; American Cancer Society Institutional Grant ACS-IN-41-I, and General Research Support Grant USPHS-5-501.

Received 4/ 9/70. Accepted 7/ 1/70.