Phenotypic Properties of Preneoplastic Rat Liver Lesions and Applications to Detection of Carcinogens and Tumor Promoters.

A variety of cellular lesions arise during liver carcinogenesis by chemicals in rats. The altered focus is a lesion of hepatocytes that occurs early in hepatocarcinogenesis and appears to give rise to both neoplastic nodules and carcinomas. Foci display numerous phenotypic abnormalities which together with nuclear abnormalities indicate that they are truly a new altered population. Using histochemical markers, the induction of foci can be measured as a quantitative index of hepatocarcinogenicity of genotoxic carcinogens. In addition, determination of the effect of agents on foci previously induced by genotoxic carcinogens can be used to assess the capacity of chemicals to act as liver tumor promoters.