The Choledochoduodenal Junction in Sheep and Goat

Abstract

The choledochoduodenal junction was studied in 15 sheep,S goats and 7 sheep fetuses by maceration technique, microdissection, and by microscopic examination. The bile duct extended from the junction of the hepatic and cystic ducts, entered the duodenum at the beginning of its descending part on the dorsomedial aspect, ran distally in the wall for about 1.5ern and ended with an opening facing distally without raising a papilla. The average length of the bile duct was 8 em j its structure along its course was also described.The wall of the bile duct acquired muscle fibers only when it approached the duodenum. These originated from the longitudinal muscle of the duodenum. As the duct passed through the duodenal circular muscle, the latter split and formed a muscular ring so that the duct at that site was surrounded by two muscle layers. When the duct coursed distally in the submucosa, it was covered with longitudinal muscle bundles on its muscle (of duodenum) surface and thin oblique and circular muscle rings on its mucosal surface and its sides. Towards the distal end of the duct, the muscle fibers on the mucosal surface decreased and finally disappeared as the duct approached the lumen of the duodenum. The fetal material confirmed the findings in the adult.The present results were discussed with the findings reported in other species. The authors believe that the structure of the choledochoduodenal junction in sheep and goat indicates the presence of a sphincter originating from and connecting with the duodenal musculature. The sphincter, therefore, should be influenced by the activity of the duodenal wall, causing flow of bile and pancreatic juices to be intermittent.