Cellular analysis of renal neoplasia: induction of renal tumors in dietary-conditioned rats by dimethylnitrosamine, with a reappraisal of morphological characteristics.

Abstract

Summary The administration of a single i.p. injection of 60 mg/kg dimethylnitrosamine (DMN) to male rats that had been temporarily fed a protein-free diet induced renal mesenchymal tumors in all animals, as well as inducing some renal adenocarcinomas. The dose of 50 mg/kg in male rats temporarily fed either a protein-free diet or a sucrose only diet or subjected to starvation resulted in an incidence of from 86 to 89% of renal tumors. Of rats maintained on a protein-supplemented diet, receiving 60 or 30 mg/kg DMN, only 35 and 18%, respectively, developed renal tumors. The morphology of the mesenchymal tumor was reappraised in terms of those histological features which either were common to all tumors examined or were features of such frequency that they could be considered characteristic of tumor development. DMN-induced renal mesenchymal tumors were not considered to be nephroblastomas, and all epithelial components other than independently developed adenomas or adenocarcinomas were consistent with pathologically altered, preexisting renal parenchyma. Attention was drawn to the vascular nature of mesenchymal tumors. These results provided a working basis for a sequential study aimed at tracing the evolution of DMN-induced renal neoplasms.