Bile ductular cells and the phenotypic heterogeneity of the population of hepatic non-parenchymal epithelial cells induced in rats by chemical carcinogens.

Single doses of diethylnitrosamine, N-hydroxy-2-acetylaminofluorene or N-methyl-N-nitrosourea were administered to rats, before or after obstruction of the common bile duct, and liver sections were stained for alpha-fetoprotein, albumin and glucose-6-phosphatase. In these animals, cells expressing hepatocytic traits were not observed in the resulting expanded population of non-parenchymal epithelial cells. A derivation of non-parenchymal epithelial cells with hepatocytic traits from bile ductular cells is not supported, but not completely ruled out, by these findings. In rats with an obstructed bile duct and administered a single carcinogen dose, serum alpha-fetoprotein was slightly increased, to levels comparable with those occurring after a partial hepatectomy. In these rats, and in partially hepatectomized rats, the cellular source of serum alpha-fetoprotein was not apparent, since no alpha-fetoprotein-positive cells were detected in their liver.