Gastroesophageal Junction: The Mucosa – Anatomy and Cell Types

Abstract

The gastroesophageal junction (GEJ) is anatomically defined by the proximal limit of the gastric folds. Histologically, it is characterized by the presence of squamocolumnar junctional epithelium. In normal conditions, the anatomic GEJ also corresponds to the histologic transition between the esophageal squamous mucosa and the gastric mucus columnar epithelium. The mucosa is composed by the lamina propria and the muscularis mucosae, both lined by non-keratinizing squamous epithelium. A short segment of the esophagus at the level of the GEJ may be lined by columnar cells that form the cardiac mucosa, although this is denied by many authors. The non-keratinizing squamous epithelium is composed of three major cell layers: a deep basal cell layer, an intermediate or prickle cell layer, and a superficial functional cell layer. CD3+ and CD8+ T-cell lymphocytes are seen in an intraepithelial location, usually above the basal cell layer.