Gastro-esophageal junction

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The gastro-esophageal junction (GEJ) (also known as the esophagogastric junction) is the part of the gastrointestinal tract where the esophagus and stomach are joined.

Gross anatomy

The GEJ is normally mostly intra-abdominal and is 3-4 cm in length. To some extent, the esophagus slides in and out of the abdomen during respiration and when there is elevation of intra-abdominal pressure.

Histology

It is comprised of two histologically distinct areas:

stratified squamous epithelium (same as the esophageal folds superiorly)
columnar epithelium (same as the gastric rugae inferiorly)

Where these two distinct areas join, there is an abrupt but non-linear change in the mucosal layer: this is called the Z-line. The non-linear, zig zagging nature of the Z-line explains that the GEJ can be several centimeters in length, while the histological transition from esophageal folds to gastric rugae is abrupt.