[Blastomogenesis in mice due to postnatal effect of N-nitrosoethylurea and x-ray irradiation]

N-nitrosoethylurea (NEU) is found to show an intensive transplacental carcinogenic effect inducing in mice different neoplasms, mainly lung adenomas. Postnatal x-ray irradiation of control animals resulted in the occurrence of ovarian tumors in some female mice. Delivary and feeding of the progeny would lead to the development of mammary gland tumors in a number of control female animals. Postnatal exposure to x-rays of mice exposed to transplacental effect of NEU resulted in the increased incidence of lung neoplasms, mainly adenocarcinomas.