抄録
The livers of fetal rats were dissociated by collagenase treatment. Twenty-four hr after the dissociation, dexamethasone (DEX) or epidermal growth factor (EGF) was added to the culture medium, and hepatocytes were cultured for 3 more days. After 3 days in culture, clear boundary lines were observed between adjacent hepatocytes in the DEX-added medium under a phase-contrast microscope. A high level of activity of gamma-glutamyltranspeptidase (GGT) was observed along these lines by enzyme histochemical staining. On the other hand, the number of hepatocytes showing a positive reaction to immunohistochemical staining of alpha-fetoprotein (AFP) was decreased in the DEX-added medium. Moreover, bundles of actin filaments were formed along the periphery of cells in hepatocytes cultured in the DEX-added medium. In addition, in the same medium, the quantity of 3H-thymidine incorporated into the hepatocytes was less than that in the pure medium or in the EGF-added medium.
When hepatocytes, cultured in the DEX-added medium, were examined under a transmission electron microscope (TEM), an accumulation of glycogen granules was observed in the cytoplasm, and bile canaliculuslike structures, consisting of large intercellular spaces, were observed between adjacent hepatocytes. In this study, it was indicated in vitro that DEX suppressed the proliferation of rat fetal hepatocytes, induced activity of GGT, and depressed the expression of AFP.
