Alterations in bile ducts and peribiliary microcirculation in rats after common bile duct ligation

The chronological changes in ductular epithelium and peribiliary capillary plexuses (PBPs) after bile duct ligation are not well understood. Therefore, we examined alterations in both intrahepatic bile ductules and peribiliary microcirculation in rats after ligation of the common bile duct using immunohistochemistry, transmission electron microscopes (TEM), and scanning electron microscopes (SEM). Ductular proliferations appeared first in the peripheral areas of the portal spaces and then gradually advanced along with increasing jaundice. Distorted configuration of the hepatic parenchyma with interconnecting stroma rich in irregular ductules developed 4 weeks after the ligation. Numerous biliary cell types and cells of types intermediate between hepatocytes and biliary cells together with poorly fenestrated capillary-type vessels appeared in the periportal parenchyma, in association with an increased number of canalicular-ductular junctions on TEM. These biliary cells were often found within the lobules and apart from the stroma. SEM examination of hepatic microvascular casts using methacrylated resin showed formation of irregular portal and periportal capillary networks, partly derived from coarsened sinusoids. Direct connections between the newly formed capillary networks and the pre-existing PBPs or sinusoids were numerous, although there were few direct connections between the capillary networks and the hepatic arterial branches. Thus, these proliferated ductules and newly formed complicated capillary networks might play an important role in the effective transport of biliary materials between hepatocytes and native bile ducts or proliferated ductules through the altered microcirculation after bile duct ligation.