Abomasum/ Glandular stomach
Author: Dr. R. Menaka
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Abomasum/ Glandular stomach
The wall of the stomach is composed of
i. Tunica mucosa
ii. Tunica Submucosa
iii. Tunica muscularis
iv. Tunica serosa
Tunica mucosa:-
a. Epithelium- Comprised of single layer of simple columnar epithelial cells. The surface epithelium is continued into depression in the gastric mucosa, known as gastric pits. The mucosal glands open into the bottoms of gastric pits, which corresponds to ducts. The oval shaped nucleus is situated in the basal part of the cell.
b. Lamina propria- which is packed with gastric glands and supported by delicate connective tissue framework. The gastric glands are of three types.
1. Fundic glands
2. Cardiac glands
3. Pyloric glands
c. Lamina muscularis- Formed by plain muscle fibers
Tunica Submucosa- Which is made up of loose connective tissue.
Tunica muscualris- is made of two layers of plain muscle. A third and inner most oblique also occurs in certain parts of the stomach.
Tunica serosa- The serous coat consists of a layer of loose connective tissue which is covered by mesothelium.
Note:
1. Fundic Glands- Each gland consist of a body which ends below in a blind and dilated extremity (the fundus) and is continued upwards into a constricted portion, known as neck. The body of fundic glands constitutes two kinds of cell. viz, Chief cells and parietal cells.
Histological features of chief cells:- Chief cells are cuboidal or pyramidal shape and contain coarse secretory (Zymogen) granules. The nucleus is spherical in shape and located in the basal part of the cell. The chief cells secrete pepsin.
Histological character of Parietal cells:- Parietal cells larger than the chief cells. They are oval or polygonal in shape and nucleus is spherical and centrally located in the cell. The parietal cells secrete hydrochloric acid.
The neck of the gland is made up of mucous cells. They are cuboidal in shape and with oval shaped nucleus, which is situated at the base of the cell.
Argentaffin cells (or chromaffine cells)- which show fine cytoplasm granules staining black by silver impregnation technique may occur as isolated cells between the basement membrane and chief cells. They said to contain serotonin, a vaso constrictor substance etc.
2. Cardiac Glands- They are highly branched and coiled, tubular glands. The ducts are very long and secrete mucous.
3. Pyloric glands- These are coiled tubular glands. A narrow eosinophilic Stohr's cells (eosinophilic columnar cells) are often found the ducts or gastric pits.
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