Esophagus

The mucosa of the esophagus is lined with stratified squamous moist epithelium to protect the organ from the partially digested food. Mucous glands are located in the lamina propria in some regions, particularly near the gastro-esophageal junction and sometimes in the upper third. The muscularis mucosae is limited or absent in the upper third, but forms a developed layer in the lower two-thirds of the esophagus.

The mucosa of the esophagus is lined with stratified squamous moist epithelium to protect the organ from the partially digested food. Mucous glands are located in the lamina propria in some regions, particularly near the gastro-esophageal junction and sometimes in the upper third. The muscularis mucosae is limited or absent in the upper third, but forms a developed layer in the lower two-thirds of the esophagus.

The mucosa of the esophagus is lined with stratified squamous moist epithelium to protect the organ from the partially digested food. Mucous glands are located in the lamina propria in some regions, particularly near the gastro-esophageal junction and sometimes in the upper third. The muscularis mucosae is limited or absent in the upper third, but forms a developed layer in the lower two-thirds of the esophagus.

The mucosa of the esophagus is lined with stratified squamous moist epithelium to protect the organ from the partially digested food. Mucous glands are located in the lamina propria in some regions, particularly near the gastro-esophageal junction and sometimes in the upper third. The muscularis mucosae is limited or absent in the upper third, but forms a developed layer in the lower two-thirds of the esophagus.

The submucosa is composed of dense, irregular connective tissue and possesses compound tubulo-acinar glands, called esophageal glands proper, scattered along the length of the esophagus. These glands, not present in this image, lubricate the esophagus during food transport.

The muscularis externa is the dominant prominent main muscle layer and is formed of inner circular outer longitudinal layers. Because swallowing is a voluntary action, the muscularis externa in the upper one-third of the esophagus is composed of skeletal muscle. Both skeletal and smooth muscle are located in the muscularis externa in the middle third (shown here), and only smooth muscle is present in this tunic in the lower one-third. The myenteric plexus (Auerbach’s plexus), a component of the autonomic nervous system, is located between the muscle layers and innervates the muscle.

The muscularis externa is the dominant prominent main muscle layer and is formed of inner circular outer longitudinal layers. Because swallowing is a voluntary action, the muscularis externa in the upper one-third of the esophagus is composed of skeletal muscle. Both skeletal and smooth muscle are located in the muscularis externa in the middle third (shown here), and only smooth muscle is present in this tunic in the lower one-third. The myenteric plexus (Auerbach’s plexus), a component of the autonomic nervous system, is located between the muscle layers and innervates the muscle.

For most of its length, the esophagus is attached to the posterior body wall and does not protrude into the thoracic cavity. Thus the outer tunic is an adventitia of connective tissue. After entering the abdominal cavity, the esophagus is covered by a serousa of visceral peritoneum.

This image was taken of a slide in the University of Michigan slide collection.