Histomorphology and microvasculature of extrahepatic bile ducts, extrapancreatic ducts and choledocho-pancreatic duct in the adult African Clawed Toad, Xenopus laevis: Histomorphology and scanning electron microscopy of microvascular corrosion casts

Abstract

The microvascular anatomy of the extrahepatic bile ducts, extrapancreatic ducts and choledocho-pancreatic duct of the adult African Clawed Toad, Xenopus laevis (Daudin) was studied by scanning electron microscopy (SEM) of vascular corrosion casts (VCCs) and light microscopy of paraffin-embedded tissue sections. Branches of the hepatic artery supplied the vascular bed of the extrahepatic bile ducts with arteries running along the serosal surface of ducts. Oblique side branches gradually invaded the bile duct walls. Terminal arterioles capillarised first in the muscular layer and finally formed a dense subepithelial capillary network. Postcapillary venules from the subepithelial capillary bed merged with those from the external layers of the duct walls and formed subserosal venous plexuses. Duct veins drained into nearby veins. The choledocho-pancreatic duct opened at the crest of a duodenal fold which at this site formed a papilla. A ring-like venule was found at the apex of this papilla. A ring-like venous plexus was located around the intraduodenal portion of the choledocho-pancreatic duct at the level of the intestinal lamina propria. Apart from these structures, microvascular patterns found closely resembled those described in mammals.