Three-dimensional morphological study of rat gastric lesions induced by N-methyl-N'-nitro-N-nitrosoguanidine. Structural atypia in carcinoma and non-carcinomatous lesions.
Lesions of the rat glandular stomach induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were classified into 4 categories: intramucosal lesions; polypous lesion; downward-growth lesions, and unequivocal adenocarcinomas. Each lesion was examined by three-dimensional reconstruction from serial sections to study the spacial arrangement of the glandular tubules. In the intramucosal lesions, the tubules showed tree-like branchings. In the polypous lesions and downward-growth lesions, the tubules were interconnected to form a three-dimensional network. In unequivocal adenocarcinomas, the tubules appeared separated and were dispersed into nests. These findings indicate that interruption of continuity of the epithelium in proliferated tubules is a possible sign of malignant transformation. Erosions were always observed in the intramucosal, the polypous and the downward-growth lesions. There were locations in the tubular system where the tubules became so attenuated as to resemble cord like structures. Inflammatory reactions were always demonstrable in the intertubular spaces in such lesions. These findings indicate that MNNG-induced anatomical changes may participate in the formation of erosions by causing local obstruction of the ductules.
D000230:Adenocarcinoma / Q000139:chemically induced / Q000473:pathology*; D000818:Animals; D005753:Gastric Mucosa / Q000473:pathology; D008297:Male; D008769:Methylnitronitrosoguanidine; D008954:Models, Biological; D011230:Precancerous Conditions / Q000139:chemically induced / Q000473:pathology*; D051381:Rats; D013270:Stomach / Q000473:pathology; D013272:Stomach Diseases / Q000139:chemically induced / Q000473:pathology*; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000473:pathology*
D008769:Methylnitronitrosoguanidine