Spontaneous Occurrence of γ-Glutamyl Transpeptidase-Positive Hepatocytic Foci in 105-Week-Old Wistar and 72-Week-Old Fischer 344 Male Rats

Abstract

Spontaneous hepatic changes in old male rats of Wistar and F344 inbred strains were studied histochemically. γ-Glutamyl transpeptldase-posttlve hepatocytic foci and cholangiolar proliferation associated with fibrosis and inflammatory infiltration were common findings in the old rats of both strains. Histochemical properties of the hepatocytes of the foci were similar to those of hyperplastic foci seen in early stages of liver carcinogenesis due to various chemical carcinogens. The incidence of the foci was 2.52/cm² of the histochemically stained sections in 105-week-old male Wistar rats and 1.60/cm² in 72-week-old male F344 rats. Altered hepatocytic foci significantly increased after 18 months of age in Wistar and F344 rats, and the presence of other spontaneous neoplastic and nonneoplastic changes was revealed.