Renal tumors induced transplacentally in the rat by n-ethylnitrosourea

We studied the renal lesions induced by transplacental administration of n-ethylnitrosourea (ENU) in the rat. In the 231 offspring we observed, 40 nephroblastomas (17.3%), 7 clear cell epithelial tumors and clear cell cystadenomas (3.0%), 183 simple cysts (79.2%), and 2 mesenchymal tumors (0.8%). Nephroblastomas showed a wide spectrum of histological appearance, and many were located in the deep renal cortex, with occasional intra-pelvic-protrusion. They showed both infiltrative and focal expansile growth without definite capsule formation. Nephroblastomas were usually unilateral, but multicentric and bilateral lesions were found in some cases. The earliest nephroblastoma was found at 4 weeks, earlier than generally described. Some of the nephroblastomas were heterotransplantable to athymic nude mice and serial transplantation was achieved in one instance. These experiments have induced a wide variety of renal tumors and tumor-like conditions, comparable to the different types of renal lesions observed in children, and may provide a useful model for the study of the pathogenesis of embryonal tumors in man.