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A review of the recent findings related to the morphological heterogeneity of …
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The intrahepatic and extrahepatic bile ducts are nourished by a complex network of minute vessels [i.e., peribiliary vascular plexus (PBP)], which originate from branches of the hepatic artery and flow principally into the hepatic sinusoids, either directly (lobular branch) or by portal vein branches (prelobular branches)[42,43]. Since the blood flows in the opposite direction (from the large towards the small ducts) to bile flow, the PBP presents a counter-current stream of biliary reabsorbed substances to hepatocytes[44,45]. We have previously shown that the function of the intrahepatic biliary tree is linked to its vascular supply sustained by the PBP[44]. Changes in intrahepatic bile duct mass are associated with changes of the PBP architecture[44]. Following BDL, the PBP undergoes hyperplasia, thus supporting the increased nutritional and functional demands from the proliferating bile ducts[44]. In support of this concept, studies[46] have shown that following chronic feeding of ANIT (which induces increases in both cholangiocyte proliferation/apoptosis)[47], the hepatic artery and portal vein undergo marked proliferation, presumably to support the increased nutritional and functional demands of the proliferated bile ducts[44,46]. However, the proliferation of the PBP occurs only after the hyperplasia of bile ducts[44]. Recent studies have shown that small and large rat bile ducts have a different vascular supply[44]. The PBP is primarily present around large bile ducts and less visible around small bile ducts[44], a finding that may partly explain why large but not small cholangiocytes proliferate following BDL in rats[48] and why small and large ducts differentially proliferate or are damaged in other experimental models of cholangiocyte proliferation/loss including chronic feeding of certain bile acids (e.g., taurocholate and taurolithocholate)[49], ANIT[47] or acute gavage administration of CCl4[50,51] (Figure 2) or partial hepatectomy[52].
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