Abstract

In an attempt to elucidate the pathological changes following common bile duct ligation, the present study was undertaken in male Sprague-Dawley rats. Morphologic studies of the livers were performed at 1, 2, 3, 5, 7, 9, 11, 13 and 15 weeks after common bile duct ligation. In an attempt to clarify the relationship between the process of bile duct formation and the nature of primitive cells observable around the primitive biliary structure, light microscopic, immunohistochemical and electron microscopic studies were performed. The results were noted as follows: 1) Light microscopically, proliferation of biliary cells began in the periphery of portal areas and expanded toward hepatic lobules. In severe cases of biliary structure proliferation, hepatocytic cords and classic hepatic lobules were inconspicuous. 2) Immunohistochemically, CK-19 expression was limited to biliary structures in protal areas and proliferated biliary epithelial cells. In the serial sections of paraffin block, proliferated intrahepatic biliary structures were associated with those of portal areas. Some oval cells in the ductular hepatocytes were stained for both CK-19 and MNF 116. 3) Ultrastructurally, the proliferated biliary epithelial cells divided into three patterns: absence of lumen, formation of incomplete lumen, and formation of complete lumen. Furthermore these patterns had spectral continuity of maturation in their structures. 4) In some biliary structures, individual biliary cells pushed the basement membrane toward neighboring tissue with accompanying destruction of basement membranes, patterns of budding. Sometimes these cells and hepatocytes comprised the same lumen. In summary, the results obtained by the present study indicate that proliferated biliary structures may be derived from the preexisting intralobular or portal biliary system.

• Keywords: Bile ductules;Ductular transformation;Rat;Bile duct ligation