Behavior of cervical epithelium during carcinogenesis: autoradiography of tritiated cytidine in the C57BL mouse.

The autoradiographic patterns of the cervical epithelia of 39 virgin C57BL mice after in vivo injection of [3H]cytidine was investigated. Of the 22 animals painted with benzo[a]pyrene for 5 months, 8 developed intraepithelial atypias and 2 had invasive carcinoma. The mean number of silver grains in individual cells increased from histologically normal cervical epithelium through atypical epithelium to invasive carcinoma. It is apparent that the autoradiographic patterns in normal, atypical, and invasive carcinoma cells reflected quantitative differences in cytidine incorporation. These differences may denote increased demand for RNA precursors in the cervical epithelium during carcinogenesis.