Digestive Tract: GIT
- Mucosa: The epithelium made of nonkeratinized stratified squamous cells. The lamina propria has diffuse lymphatic tissue and lymphatic nodules. The muscularis mucosae is composed of ONE layer of longitudinally organized smooth muscle.
- Submucosa is along with the muscularis mucosae, forming longitudinal folds and creating a very irregular luminal profile when seen in XS.
- Muscularis externa: the upper ⅓ is striated muscle, the middle third is striated and smooth muscle interwoven, and the lower third is smooth muscle continuous with the rest of the gut.
The esophagus has adventitia until it enters the abdominal cavity, then it is covered by serosa. There are two types of esophagus glands:
- Esophageal glands proper, which occur in the submucosa and are scattered throughout the length of the esophagus (mostly in the upper one half). They are small, compound tubuloalveolar glands that produce acidic mucus.
- Esophageal cardiac glands occur in the lamina propria of the mucosa. They are similar to cardiac glands of the stomach. They present in the terminal part of the esophagus and produce neutral mucus to protect against regurgitated material.