Production of proliferation lesions in gastric mucosa of albino mice by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine.

It was possible to produce gastric adenocarcinoma in five of 69, healthy, young albino mice of both sexes given N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in their drinking water at a concentration of 100 microgram/ml. The tumoral lesions were most clearly defined in the group that received MNNG for the longest period of time, that is, 68 weeks. On the other hand, in the rest of the groups, which received MNNG for fewer weeks, there were lesions found in a total of nine animals which consisted in foci of typical and atypical hyperplasia, erosion of the mucosa, and, in one animal, an adenomatous polyp. Contrary to findings in humans, intestinal metaplasia preceding or accompanying the neoplasia was found to be an inconsistent alteration and a not very frequent one.