Combined radiographic, manometric, and histologic localization of the canine lower esophageal sphincter

Abstract

The localization of the lower esophageal sphincter at the canine esophagogastric junction was investigated by employing radiopaque sutures as reference points for a combined radiographic, manometric, and histologic study. The three reference points were: the junction of squamous and columnar epithelium, the point where the tubular esophagus joins the saccular stomach, and the inferior margin of the diaphragmatic erura which separates the peritoneal cavity from the erural canal. Radiographically, the squamocolumnar epithelial junction was midway between the esophagogastric junction and the abdominal margin of the esophageal hiatus. Manometrically, the high-pressure zone (HPZ) extended above, as well as below the squamocolumnar epithelial junction. The manometric limits of the HPZ correspond to the thickened band of circular smooth muscle comprising the upper circular fibers of the gastric sling (sling of Willis). These fibers constitute the lower esophageal sphincter and lie between the esophagogastric junction and the abdominal margin of the esophageal hiatus.