[The effect of disorders of the estrous function in female rats on the realization of multigenerational carcinogenic effect of N-nitrosomethylurea].

The F1 female rats exposed to N-nitrosomethylurea (NMU) in dose 20 mg/kg on the 21st day of gestation and postnatal induction of persistent estrus syndrome revealed an increased incidence of tumours of the central nervous system (CNS) as compared to F1 exposed to NMU transplacental action only (25.0-2.5%, respectively). Carcinogenic effect was observed in F2 females as well, and was manifested in the development of malignant tumours of the nervous system and kidney but with a lower frequency than in F1 rats. The same modifying factors--persistent estrus syndrome--did not produce any significant effect on carcinogenesis in F2 animals.