Mucosa of esophagus

The mucosa of esophagus is the innermost layer of the esophageal wall and is adapted to protect against mechanical abrasion during the passage of food.

Components of the esophageal mucosa

1. Epithelium

• Lined by nonkeratinized stratified squamous epithelium.

• Provides protection against friction and trauma from swallowed food.

• Unlike the skin, it lacks a keratin layer, helping maintain flexibility and moisture.

2. Lamina propria

• A layer of loose connective tissue beneath the epithelium.

• Contains blood vessels, lymphatics, immune cells, and occasional mucous glands, particularly near the gastroesophageal junction.

3. Muscularis mucosae

• A thin layer of longitudinal smooth muscle, that becomes thicker toward the distal esophagus.

• Facilitates local movement of the mucosa and aids glandular secretion.

Histological Features

• The mucosa forms longitudinal folds, allowing expansion during swallowing.

• At the gastroesophageal junction, the lining abruptly changes from nonkeratinized stratified squamous epithelium (in esophagus) to simple columnar epithelium (in stomach).

Clinical Relevance

• In case of gastroesophageal reflux disease (GERD), the chronic acid exposure could damage the squamous mucosa of esophagus.

• A condition called the Barrett's esophagus could result as a result of longstanding inflammation (for instance, during GERD) that is characterized by replacement of normal squamous epithelium by intestinal type columnar epithelium with goblet cells (intestinal metaplasia). This is a pre-malignant condition and could increase the risk of esophageal adenocarcinoma.