Title: Digestive system – Histology
Headings: 12
Digestive system

12 Digestive system
Four layers of digestive tract walls
Mucosa
Submucosa
Muscularis externa
Adventitia
Regional histology of the digestive tract
Esophagus
Stomach
Small intestine
Large intestine
Region
Histological characteristics
Esophagus
Stomach
Small Intestine
Large Intestine

Content: The image is of the esophagus from above. Regional histology of the digestive tract
Esophagus
The esophagus is a long, soft tube that connects the pharynx to the stomach. Its only function is the transport of food. The mucosal surface of the esophagus is lined by a thick layer of stratified squamous epithelium, adapted for fast transport and withstanding abrasive forces of moving food pieces. The muscularis is well developed as the esophagus’ peristalsis has to push food toward the stomach. In the upper segment of the esophagus, the muscularis layer contains mostly skeletal muscle that transitions to a mixture of skeletal and smooth in the middle, and finally only smooth muscle in the lower part. The characteristic features of the esophagus are the combination of stratified squamous epithelium and the considerable thickness of the muscularis mucosae, much thicker than in other parts. Figure 5: Stratified squamous epithelium of the esophagus
Stomach
The stomach is a muscular sack for the storage and digestion of food. The stomach can be divided into three regions: