[Characteristics of the action of N-nitrosoethylurea in rat embryogenesis]

Based on the experiments with single intravenous injections of NEU in rats with definite pregnancy terms, it was found the embryos are especially sensitive to embryotoxic effects at the 3d--4th and 9th day, to teratogenic effects--at the 9th--14th day. The carcinogenic effect of NMU (20 mg/kg) is evident following the exposure, starting from the 11th day of embryogenesis, and the former is equally maximum during the subsequent terms until the end of the intrauterine period, their offsprings developing multiple tumors of the central and peripheral nervous systems. The sensitivity of rat embryos to NMU carcinogenic effect, contrary to the embryotoxic and teratogenic ones, showed no strict staging character. No correlation was noted between gross developmental defects and the appearance of tumors.