Somatostatin-containing cells in the extrahepatic biliary tract of humans.

We investigated the presence of endocrine cells in the human extrahepatic biliary system using the avidin-biotin-peroxidase complex method. Twenty gallbladders obtained during operations for cholelithiasis, large portions of three common bile ducts obtained during Whipple's procedure for carcinoma of the head of the pancreas, and 155 endoscopic transpapillary biopsy specimens taken during control endoscopy from patients who had had a previous endoscopic sphincterotomy were examined. Somatostatin-containing cells were found in the glandular epithelium of the ampulla of Vater and the bile ducts. Only the surface epithelium in the ampulla contained endocrine cells. All somatostatinlike immunoreactivity was confined to cells and could not be detected in nerves. No somatostatinlike immunoreactivity was found in the gallbladder. These findings reveal a morphologic basis to reported actions of somatostatin on bile flow.