Sphincter of the hepatopancreatic ampulla (Oddi): A morphological study

The precise morphology of the human sphincter of Oddi was investigated. Anatomic samples, including the terminal portion of the bile duct and main pancreatic ducts, the major duodenal papilla, and the periampullary duodenal wall, were removed from 22 cadavers of various ages of patients who had died without any history of biliary or pancreatic disease. The specimens were fixed and processed by routine techniques and examined by light microscopy; serial sections were stained with haematoxylin-eosin, Masson's trichrome, and Van Gieson methods. The muscular bundles of the human sphincter of Oddi were divided into the following tracts: The X-Y tract, the distance from the papillary opening to the first muscular thickening that showed a circular trend; the Y-Z tract, the thickest portion of the circular muscular bundles (the true sphincter of the hepatopancreatic ampulla( (HPA) (Oddi), reinforced by fibres arising from the duodenal wall and the Z-W tract, the terminal thinner portion of the circular bundles that pass from the duodenal wall to the bile duct. The X′, Y′, Z′, and W′ points were fixed by the same criteria along the wall of the main pancreatic duct. The single tracts were measured, and the data derived therefrom subjected to statistical analysis.