MORPHOLOGICAL ANALYSIS OF ACUTE ULCERATIVE-COLITIS EXPERIMENTALLY-INDUCED BY DEXTRAN SULFATE SODIUM IN THE GUINEA-PIG - SOME POSSIBLE MECHANISMS OF CECAL ULCERATION

This study in the guinea pig demonstrated that ulcerative colitis-like lesions were induced more rapidly and effectively than in other labor atory animals by the oral administration of dextran sulfate sodium (DS S). In all guinea pigs receiving 3% DSS solution, diarrhea was noted w ithin 48 h, and bleeding at 48-72 h. Light microscopically, hemorrhagi c and ulcerative lesions were observed in the cecum and proximal colon as early as 72 h after administration. Lamina propria macrophages, ga ther in the subepithelial region under normal conditions, were markedl y increased in number after DSS administration; by 96 h, they were app roximately three times as many as in the control specimens. The cecal mucosa was also characterized, in earlier stages, by the obliteration of virtually all crystal lumina because of the accumulation of mucous secretions, leading to the subsequent disappearance of the crypts. The obliteration of crypts, which preceded the increase of macrophages, i s suggested to play a leading part in this ulceration.