[Estimation of proliferative activity of experimental tongue papillomas and carcinomas in rats--comparison with DNA cytofluorometric analysis and silver-stained nucleolar organizer regions].

Eleven tongue papillomas and 25 tongue carcinomas were produced in rats by the oral administration of 0.001% 4-nitroquinoline 1-oxide (4 NQO) in drinking water, and tumor kinetics were investigated by both DNA cytofluorometry and Ag-nucleolar organizer regions (Ag-NORs) staining. The histopathologic characteristics, the mean Ag-NOR number per cell and DNA ploidy patterns were compared. The mean Ag-NOR number was least in normal epithelium, more numerous in papillomas and highest in squamous cell carcinomas. The differences were statistically significant. All cases of normal epithelium and papilloma showed a diploid pattern. Eighteen cases of the squamous cell carcinomas (72%) showed a diploid pattern, and 7 cases (28%) exhibited a diploid plus tetraploid pattern. There was a significant difference in the mean Ag-NOR number between the two groups of squamous cell carcinomas. These results suggest that the mean Ag-NOR number may reflect the cell kinetics in the process of carcinogenesis and polyploidization of carcinomas.