The peribiliary vascular plexus: the microvascular architecture of the bile duct in the rabbit and in clinical cases.

The livers of 30 rabbits were perfused with a silicone rubber solution (Microfil), underwent a clearing process, and were examined with a dissection microscope. The study showed distinct vascular plexuses in and around the bile duct, and two concentric vascular layers present within its wall: the inner capillary and the outer venous. Around the bile duct there was a fine arterial network and a larger venous plexus, which communicated with the capillary and venous plexuses of the bile duct, respectively. The venous plexuses drained directly into the sinusoids or indirectly through the portal vein. The microvascular architecture of the rabbit bile duct correlated well with clinical angiograms exhibiting normal and abnormal peribiliary vascular plexuses. The arterial and venous plexuses dilated and provided collateral circulation in both extrahepatic and intrahepatic arterial and portal vein occlusions, respectively. The peribiliary arteries may be dilated or encased in patients with cholangiocarcinoma or hepatocellular carcinoma invading the bile duct. The animal study and observations on angiograms suggest the existence of transplexal arterioportal communication.