Carcinogenesis in forestomach and changes in oral mucosa of rats induced by intragastric N-methylnitrosourea.

It is well known that oral administration of N-methylnitrosourea (NMU) induces carcinomas in the forestomach of experimental animals. As the rat forestomach is lined with an orthokeratinized squamous epithelium the purpose of the present study was to elucidate whether carcinogenesis in this localization following intragastric application of NMU was comparable to oral carcinogenesis in experimental animals and humans. Furthermore, the development of oral mucosal lesions in the rats was studied. It is concluded that the morphologic changes seen during carcinogenesis in the forestomach do not seem to differ essentially from those seen during experimental and human oral carcinogenesis. Furthermore, the number of oral lesions found in the present study are higher than reported in other strains of rats following administration of NMU.