Tumor Induction in Transplanted Mammary Glands in Rats2

Abstract

Mammary glands were successfully transplanted from randombred Sprague-Dawley rats to recipients, irrespective of whether the transplants were autografts or homografts. Homologous transplantation of mammary glands was successful in both littermates and nonlittermates. Surviving grafts had the histological appearance of normal mammary glands and functioned like the normal mammary glands of the recipients. The grafts showed extensive lobular-alveolar growth, secreted milk when the graft-bearing rats were pregnant, and atrophied, as the mammary glands of the recipients did, when their ovaries were removed. When female rats were fed a single dose of 7,12-dimethylbenz[a]anthracene (DMBA) and their mammary glands were subsequently transplanted into female recipients, mammary cancer developed in the mammary grafts in the hosts. Mammary cancer developed in a gland transplanted to a recipient as soon as 4 hours after the donor was fed a single dose of DMBA. The incidence of tumors was significantly lower in mammary grafts from male donors than from female donors. Mammary tumors developing in such grafts are hormone-dependent, since they regress after excision of the ovaries.