gastric mucosa

WP

Definition: The gastric mucosa is the mucous membrane layer of the stomach which contains the glands and the gastric pits. In humans it is about 1 mm thick and its surface is smooth, soft, and velvety. It consists of epithelium, lamina propria, and the muscularis mucosae.

Types

 fundic mucosa
 antral mucosa
 pyloric mucosa

Surface of the mucous membrane

The surface of the mucous membrane is covered by a single layer of columnar epithelium . This epithelium commences very abruptly at the cardiac orifice, where there is a sudden transition from the stratified epithelium of the esophagus.

The epithelial lining of the gland ducts is of the same character and is continuous with the general epithelial lining of the stomach.

An important iodine-concentration by sodium-iodide symporter (NIS) is present in mucinous cells of surface epithelium and gastric pits of the fundus and pyloric part of the stomach.

Gastric glands

When examined with a lens, the inner surface of the mucous membrane presents a peculiar honeycomb appearance from being covered with funnel-like depressions or foveolae of a polygonal or hexagonal form, which vary from 0.12 to 0.25 mm. in diameter. These are the ducts of the gastric glands, and at the bottom of each may be seen one or more minute orifices, the openings of the gland tubes.

Gastric glands are simple or branched tubular glands that emerge on the deeper part of the gastric foveola, inside the gastric areas and outlined by the folds of the mucosa.

There are three types of glands:
 cardiac glands (in the proximal part of the stomach),
 oxyntic glands (the dominating type of gland),
 pyloric glands.

 cardiac glands

• The cardiac glands mainly contain mucus producing cells.

 oxyntic glands

• The bottom part of the oxyntic glands is dominated by zymogen (chief) cells that produce pepsinogen (an inactive precursor of the pepsin enzyme).
• Parietal cells, which secrete hydrochloric acid are scattered in the glands, with most of them in the middle part.
• The upper part of the glands consist of mucous neck cells; in this part the dividing cells are seen.

 pyloric glands

• The pyloric glands contain mucus-secreting cells.

Several types of endocrine cells are found in all regions of the gastric mucosa:
 The pyloric glands contain gastrin producing cells (G cells); this hormone stimulates acid production from the parietal cells.
 ECL (enterochromaffine-like) cells, found in the oxyntic glands release histamine, which also is a powerful stimulant of the acid secretion.
 The A cells produce glucagon, which mobilizes the hepatic glycogen.
 The enterochromaffin cells produce serotonin, which stimulates the contraction of the smooth muscles.

Pathology

 gastric mucosal anomalies

• inflammation: Gastritis
• infiltration
  • infiltration of gastric mucosa by smooth muscle cells
  • infiltration by abnormal cells

 gastric mucosal lesional syndromes

 gastric mucosal diseases

See also

 pylorus
 digestive mucosa

• gastric mucosa
  • cardial mucosa
  • fundic mucosa
  • antral mucosa