[Transplacental oncogenic effect of ethylnitrosourea in rabbits (author's transl)].

50 mg/kg ethylnitrosourea (ENU) per dose, diluted in a 0.9%NaCl/1%NaH2PO4 solution (pH 6.2) were administered intravenously to three pregnant rabbits. The injections were carried out on the following days of gestation: 21., 26., and 30./21., 25., and 31./22., 25., and 30. From the total offspring (22), 16 rabbits could be raised. In 12 animals, kidney tumours were observed after a latent period of 2--2 1/2 years. The induced tumours are generally composed of both epithelial and mesenchymal tissue elements. Two tumours of the series are of a pure epithelial or a pure mesenchymal nature respectively. In most of the mixed tumours, classified as Adenocarcino-Sarcomas (10), the epithelial and mesenchymal elements are closely integrated, sometimes one component predominated over the other one. Histologically the ENU-induced mixed tumours of kidney in rabbits and the "dysontogenetic" kidney tumours of children (WILMS) show comparable structural characteristics.