Quantitative assessment of the rat intrahepatic biliary system by three-dimensional reconstruction

The anatomical details of the biliary tree architecture of normal rats and rats in whom selective proliferation was induced by feeding alpha -naphthyL isothiocyanate (ANIT) were reconstructed in three dimension using a microsc opic-computed tomography scanner. The intrahepatic biliary tree was filled with a silicone polymer through the common bile duct and each liver lobe em bedded in Bioplastic; specimens were then scanned by a microscopic-computed tomography scanner and modified Feldkamp cone beam backprojection algorith m applied to generate three-dimensional images. Quantitative analysis of bi le duct geometry was performed using a customized software program. The dia meter of the bile duct segments of normal and AMT-fed rats progressively de creased with increasing length of the biliary tree. Diameter of bile ducts from ANIT-fed rats (range, 21 to 264 mum) was similar to that of normal rat s (22 to 279 mum). In contrast, the number of bile duct segments along the major branch reproducibly doubled, the length of the bile duct segments dec reased twofold, and the length of the biliary tree remained unchanged after ANIT feeding. Moreover, the total volume of the biliary tree of ANIT-fed r ats was significantly greater (855 mul) than in normal rats (47 mul) Compar ed with normal rats, the total surface area of the biliary tree increased 2 6 times after ANIT-induced bile duct proliferation. Taken together, these o bservations quantitate the anatomical remodeling after selective cholangioc yte proliferation and strongly suggest that the proliferative process invol ves sprouting of new side branches Our results may be relevant to the mecha nisms by which ducts proliferate in response to hepatic injury and to the h ypercholeresis that occurs after experimentally induced bile duct prolifera tion.