[What is the esophagogastric junction?].

The esophagogastric junction is a muscle, not a mucosal, junction. The boundary of the esophagus is at the upper esophageal sphincter and lower esophageal sphincter (LES) at the oral and anal ends, respectively. The distal end of the LES is the esophagogastric junction. Fine palisade vessels occur in the mucosa above the LES, and the esophagogastric junction is at the distal end of this palisade zone. The esophagogastric junction is defined as the part changing into the lumen seen in radiographic, examination or in surgically resected specimens. It is extremely difficult to identify the esophagogastric junction pathologically, requiring special effort.