THE STOMACH CELLS
The stomach has many cells, each of which functions according to its function and location.
1-The Gastric Mucosa Barrier.
Deeply located in the stomach on top, followed by the submucosa and the muscularis ; its role is to protect the stomach against an acid pH by a continuous layer of cells which synthesize mucigene. This mucigene is excreted on the surface of the epithelium, where it transforms into mucus. This barrier includes mucus gel, bicarbonate and surfactant phospholipids.
*The gastric mucosa is formed by:
— Epithelial cells are continuities of cells forming a layer encompassing the superficial epithelium, crypts and glands.
— The chorion, or lamina propria, is a richly vascularized and innervated connective tissue, located in the middle of the superficial epithelium and the muscular mucosa.
— The muscularis mucosa, a thin layer of smooth muscles crossed by blood vessels, lymphatics and nerve threads intended for the epithelial cells and the chorion.
2-Digestive Cells.
The superficial gastric epithelium uniformly lines the gastric lumen from the cardia to the pylorus and is divided from top to bottom into 3 parts:
— The fundus has an arc shape; it includes, in its densest part, the parietal cells and the principal cells. The fundus is the environment of the tubular or gastric glands. The tubular glands occupy most of the stomach, they secrete hydrochloric acid and pepsin.
The gastric glands have three types of cells: mucus cells, border cells and parietal cells.
— Mucus cells cover the apical surface of the stomach and line the crypts into which the gastric glands open.
— The bordering or parietal cells are found all along the gastric glands, they are more numerous in the middle part of the stomach.
— The distribution of cells at the level of the fundus is quite similar, the density of parietal cells is enormous near the greater curvature and thin in the opposite.
— The principal cells or pepsin constitute the main cell type of the lower third of the gastric glands. They are more numerous and smaller than the parietal cells.
— The cardia area. It lies laterally and behind the esophageal tube and internally in the stomach. In its depth, there are mucus cells.
— The antrum region does not contain parietal cells, but essentially mucus cells.
3-Pyloric Glands.
These glands are tubular. The cells that compose them are mucus cells.
4-Endocrine Cells.
Unlike the previous cells which produce the external secretion of the stomach, endocrine cells discharge their secretion products directly into the blood. They exist throughout the gastric mucosa. Few, they are always located in the middle or deep part of the glandular tube.
They are disseminated between the various types of cells with exocrine function. They share characteristics with those of other endocrine cells of various tissues such as pancreas, parathyroids, pituitary gland, adrenal medulla : capacity to capture amine precursors, DOPA and hydroxytryptophan, presence of an amino acid decarboxylase, richness in non-specific esterases and, or in cholinesterases.
— G cells.
They secrete gastrin. They are located mainly in the antrum, more rarely in the duodenum and disappear beyond the duodeno-jejunal angle.
Absent at the level of the fundus, they are located at the level of a middle third of the glandular tubules, generally dispersed between the mucus cells, more rarely grouped in around ten per tube, although the number of cells per glandular tube can vary from one portion to another of the gastric antrum.
— Enterchromaffin Cells.
They are numerous in the antrum and duodenum, and all along the digestive tract. They protrude from the periphery of the glandular tube. Their apical extension reaches the glandular lumen. Their secretion granules contain 5-hydroxytryptamine or serotonin.
Alongside the former, we find so-called enterochromaffin-like cells. They are practically absent from the human antrum, but present in the fundus.
— D Cells.
Quite numerous in the antrum and fundus, they can produce somatostatin.
