A new anatomical insight into the architecture of biliary duct system, gall bladder, and Duodenal Papilla with the extrahepatic bile ducts of white pekin duck (Anas platyrhynchos).

The study was prepared to explain the morphological features of the biliary duct system, gall bladder, duodenal papilla, extrahepatic ducts, and pancreatic ducts of the white Pekin Duck (Anas platyrhynchos) using gross, casting, ultrastructural, and histochemical techniques. The gall bladder in the liver's cystic fossa is not visible from the right lobe's parietal surface. Bile is drained from the liver via the intrahepatic bile duct, with one main duct in the left lobe branched into two secondary ducts and three hepatic ducts in the right lobe. The hepatocystic duct transports bile to the gall bladder, joins the hepatic ducts, and opens in the bile sinus. The duodenal papilla is a small, non-elevated structure in the duodenal mucosal lining, containing the glands and surrounded by columnar epithelial cells and thick microvilli. The pancreatic ducts, surrounded by a thick muscular layer and opening on the elevated side of the papilla, is lined with simple epithelium and goblet cells, with microvilli. The gall bladder is composed of tunica mucosa, muscularis, serosa, and adventitia, with a simple columnar epithelium, small brush borders, and a striated border of microvilli. The hepatoenteric duct is covered by simple cuboidal epithelium, and the mucosa forms folds along its luminal surface without the mucosa lamina muscularis. The cystoenteric duct is lined with tall columnar epithelium, with a twisted wall and numerous smooth muscle fibers. PAS exhibited positive reactions for all structures. In conclusion, research on the duck biliary system is vital for understanding avian digestive mechanisms, benefiting veterinary medicine and conservation efforts.