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: 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: fundus
body
pylorus
Each stomach region contains slightly different mucosa that reflects their different function. At the junction with the esophagus, the stratified squamous epithelium of the esophagus abruptly changes to the simple columnar epithelium of the stomach. Simple columnar epithelium is recognizable by the shape and position of the nuclei. They are elongated and arranged in a neat, single row along the basement membrane. Figure 6: