EN
A long-term use of oral contraceptives may be responsible for an increased risk of benign hepatic tumors (hepatic adenoma, focal nodular hyperplasia (FNH), hemangioma). The purpose of this study was to determine the effect of estrogen administration on the liver function and morphology. Oestradiolum benzoicum was administered intramuscularly to female rats for 8 weeks. Liver sections were collected for histological and ultrastructural examination. The most common features were as follows: nodular regenerative hyperplasia, adenomas, peliosis hepatis and fatty changes. In animals which had received higher than therapeutic doses of estrogens the following ultrastructural changes were found: mitochondrial damage, megamitochondria, diffusely distributed round spaces with blood fluid inside, fatty changes, canalicular cholestasis and steatohepatitis with Ito cells. Data derived from this model should provide more accurate information useful in recognizing hepatotoxicity of a drug during initial toxicological studies and during initial evaluations in man before widespread clinical use, as well as in determining the risk of liver tumor development.