[Effect of the postnatal induction of persistent estrus on the realization of the transplacental action of DMBA in 1st- and 2d-generation rats].

In rats of the first generation subjected to transplacental DMBA action with subsequent (at the age of 3 months) induction of persistent estrus, the incidence of tumours significantly increased, particularly, those of the nervous system and the mammary gland. Rats of the second generation with induced persistent estrus and not exposed to DMBA developed neoplasms of the nervous system and kidneys which were not observed in the intact control animals. This fact suggests persistence of DMBA transplacental carcinogenic effect in a series of generations.