Induction of Mammary Cancer in Agent-Free Mice Bearing Pituitary Isografts Correlated With Inherited Hormonal Mechanisms2

Abstract

Mammary cancer was induced by the subcutaneous implantation of pituitary isografts in agent-free females of strains C3Hf and BALB/c and F₁ hybrids of several crosses. Some ovariectomized females became cancerous when they were the recipients of pituitary isografts, as did some castrated males implanted with pituitaries alone or ovaries and pituitaries. Some mammary tumors contained a milklike secretion, several were diagnosed as adenoacanthomas or adenomas, and adrenocortical alterations were seen in gonadectomized animals bearing isografts, which included ovaries. Only (Af × C57BL/4)F₁ hybrids as a group did not develop mammary cancer when subjected to these different hormonal influences. An association was seen between the induction of mammary cancer in agent-free mice with hypophyseal isografts and the presence of an inherited hormonal pattern that would produce a high incidence of tumors in virgin females having other inciting factors (mammary-tumor agent and susceptibility). The development of adrenocortical lesions in gonadectomized animals of some groups when they received pituitary and/or ovarian grafts might suggest some abnormal hormonal activity and/or function.