Acceleration of neoplasms of reticular tissue with syngeneic thymic graft under renal capsule and gamma radiation.

Weanling ICRC female mice were given syngeneic neonatal thymus graft under renal capsule and two weeks later whole-body gamma-radiation (group ITR). The findings on ITR were compared with three controls--untreated (C), thymus grafted (IT) and irradiated (IR). In ITR group 15/15 developed generalized neoplasms of reticular tissue at 5 to 8 months and single mammary tumor at 7 months. In IR group 12/13, 21/25 in IT and 5/23 in C had neoplastic changes at 7-month onwards. Microscopically these neoplasms had diffuse or focal proliferation of modified reticulum cells, histiocytes, lymphocytes and giant cells. Localized thymic tumors showed either the same picture or prominence of small lymphocytes. Mammary tumors developed in 12/25 IT, and 8/25 in C and nil in IR.