Adenomatous changes and adenocarcinoma of glandular stomach in Wistar rats induced by N-methyl-N'-nitro-N-nitrosoguanidine. An electron microscopic and histochemical study.

Adenomatous changes, and early and invasive carcinomas of the glandular stomach in Wistar rats ingesting N-methyl-N'-nitro-N-nitrosoguanidine were studied. Almost all adenomatous changes and carcinomata were located near the midpoint of the lesser curvature. In electron microscopic and histochemical studies, both changes showed great cytological similarity. Electron microscopically, they were found to consist of predominantly undifferentiated cells with poorly developed cytoplasmic organelles, with some highly differentiated cells present. Histochemically, both showed strongly positive reactions for lysosomal enzymes. For tumor transplantation, five lesions were used and in all cases, the transplants were successful.