[Effect of N-nitrosoethylurea dosage and postnatal x-ray irradiation on transplacental blastomogenesis in mice].

In transplacental exposure to nitrosoethylurea in a dose of 2 mg/Kg the frequency of occurrence of different neoplasms in mice would not change as compared with a dose of 20 mg/Kg. However, in a dose of 2 mg/Kg the time of lung tumor development was prolonged. Postnatal roentgen irradiation increased the incidence of lung adenomas and ovarian tumors in female mice, exposed in embryogenesis to NEU effect in a dose of 2 mg/Kg; male mice showed a somewhat delayed development of tumors. In animals, subjected to NEU effect transplacentally in a dose of 20 mg/Kg, postnatal roentgen irradiation resulted in the appearance of lung adenocarcinomas, tumors of other lacolizations being developed neither in female nor in male mice.