The normal anatomy around the oesophagogastric junction: a histopathologic view and its correlation with endoscopy

The incidence of primary oesophageal adenocarcinoma in Caucasian men has recently been increasing rapidly. Therefore, primary oesophageal adenocarcinoma, columnar-lined oesophagus (CLO) or Barrett's oesophagus and the normal condition of the lower segment of the oesophagus are currently receiving worldwide attention in the medical field. Precise definitions of the anatomical features of the oesophagogastric junction (OGJ) are essential before accurate assessment of CLO can be made. This article reviews the normal morphological features in the OGJ zone to give a closer insight into the histopathology and endoscopic appearance of the OGJ and CLO. We review definitions of the OGJ, the pattern of the squamocolumnar junction (SCJ), oesophageal cardiac-type glands beneath the squamous epithelium, the normal squamous epithelium, columnar islands in squamous-lined mucosa, squamous islands in CLO and newly reported metaplastic changes in the OGJ zone. The nature of the OGJ is clarified in detail through comparison between endoscopically evident and histological features.