The incidence of cancer in quantitatively transplanted mammary glands and its relation to age and milk agent of the donor and host mice.

Western Ontario, London, Ontario, Canada. Received for publication October 28, 1964; revised May 21, 1965. fluence of hormonal stimulation and Nandi (42) empha sized the importance of the milk agent in inducing hy PerPlastic alveolar nodules and eventual tumor. 1\Iice without the milk agent may be infected by ingestion or injection of milk, by injection of semen (5, 38), or by transplantation of mammary tumor and other tissues (7) so that they subsequentlyacquiremammarycancers. But milk-agent-free mice may also develop mammary cancer without being infected with the milk agent (23). The infectivity of the milk agent and development of mammary cancer in mammary grafts from milk-agent free donors in agent-positive host mice or in mammary glands of the hosts of milk-agent-free mice receiving grafts from milk-agent-positive donor mice were studied in con junction with different hormonal influences.