The purpose of this study was to investigate the morphologic changes of the bile canaliculi and its associated structures of the liver induced by common bile duct ligation(CBDL) in the rat. The canalicular surface and lateral surface of the dry-fractured hepatocytes was studied with scanning electron microscopy at 1~6 weeks post ligation. The first week after CBDL, the bile canaliculi were dilated. The microvilli were increased in number and the lumens contained granular materials After 2 weeks or more, the bile canaliculi were dilated to a variable degree, and with irregularity, measuring from 1.5 to 5 micrometer in diameter, and in the advanced stage, the canaliculi showed blunting and the disappearance of microvilli. Some canaliculi had sprouting side branches. At 4~6 weeks post-ligation, the lateral surface of the hepatocytes also showed some irregularity and a tortuous appearance, and numerous small sized microvillous projections were formed. The tubular structures of the proliferated SER distributed adjacent to the lateral surface of the hepatocytes, and the direct connection of a tubular structure and the cytoplasmic membrane was observed. These results suggest that the deformity and loss of microvilli of bile canaliculi reflect the disturbance of bile secretion from the hepatocytes. And prolonged obstruction of bile flow may result in bile excretion via the lateral surface of hepatocytes.
To clarity the effect of biliary obliteration on copper metabolism of rat liver and on the hepatic morphology, 0.5% cuppuric sulfate was administered intraperitoneally for 42 days following ligation of the common bile duct (CBD) of Sprague-Dawley rats. The blood copper concentration, the hepatic copper content and the accumulation patterns of copper and copper binding protein in the liver were examined and compared with those of the simple CBD ligation group and the simple copper over loaded group. CBD ligation induced marked proliferation of bile ductular structures which, after expanding the portal tracts, invaded and divided the hepatic lobules. There was, however, no excess fibosis beyond what needed to support the new ductules. The blood copper concentration and the hepatic copper content were increased by copper overload with or without CBD ligation, particularly incases with CBD ligation. Liver cell necrosis did not occur by the overloaded copper alone in rats. The hepatic copper and copper binding protein were accumulated at periportal liver cells in the group of coppe overload after CBD ligatio, whereas they began to appear at perivenular hepatocytes in the simple copper overloaded group. In conclusion, it is suggested that CBD ligation does not induce excess fibrosis or liver cirrhosis in rat as far as during our experimental period, but affect significantly on copper metabolism by intrahepatic redistribution of the copper and the copper binding proteins.