[Influence of anticarcinogenic agents on the transplacental carcinogenic effect of N-nitroso-N-ethylurea].

Experiments on rats were made to study the action of 7 anticarcinogenic substances administered postnatally for a long time (sodium selenite, retinol acetate, phenformin, amber acid, low-molecular polypeptide factors of the thymus, pineal gland, and bone marrow) on the transplacental carcinogenic effect of N-ethyl-N-nitrosourea (ENU) The polypeptide factors of the thymus and pineal gland and phenformin inhibited the development of nervous system and renal tumors induced transplacentally by ENU. The rest of the substances did not influence the transplacental carcinogenesis.