Nuclear DNA content in dimethylhydrazine-induced colonic carcinoma and mucosal dysplasia in rats.

Mucosal dysplasia and carcinoma infiltrating the submucosal layer were induced in rats with dimethylhydrazine. The nuclear DNA content of the cells was measured, and the correlation between the DNA distribution pattern and histopathologic findings was evaluated. In mild and moderate dysplasias, histograms of the nuclear DNA content showed a narrow range of distribution with a sharp peak in the diploid area. In severe dysplasia, however, there was wide distribution and no peak value; this was reminiscent of carcinoma. Based on the findings of this report, the authors suggest that severe dysplasia be regarded as intramucosal carcinoma.