Stomach is Alimentary canal The expansion part has the function of storing food Digestion And push food in duodenum Role of. Ruminant The stomach of（ Restoring stomach ）, consisting of four parts: rumen （rumen）、 Reticulum （reticulum）、 Omasum stomach (omasum) and abomasum, the first three parts are collectively called Anterior stomach （forestomach）， mucous membrane None inside Glands ， epithelium by Stratified squamous epithelium , relying on mechanical and chemical action Crude fibre Sex food is broken down into absorbable nutrients. The abomasum is located at the bottom of the right abdomen of ruminants, connecting the omasum above and the duodenum below. The epithelium of abomasum mucosa is Monolayer columnar epithelium The mucosa contains glands. The ruminant ruminant has a mucosal layer Submucosa , muscularis and Serous membrane four layers [1-3] 。 his Digestive gland The body is mainly distributed at the fundus of stomach and pylorus Division, mainly including hydrochloric acid 、 Pepsin and Rennet Etc acidic ， Ph value About 1.05-1.32, except for feed protein In addition to digestive function, abomasum gastric juice It can also kill Chyme Microorganisms in the diet provide nutrition for ruminants. mucous membrane Layer is stomach Chemistry Digestion The most important part. Stomach in Empty In the state, the muscularis mucosa shrinks, gastric mucosa The surface is allowed to be vertical and horizontal Plica When the stomach is full of food, these folds become smaller or disappear. Ruminant The abomasum mucosa consists of epithelium , lamina propria and muscularis mucosa. Mucosal epithelium
The epithelium of abomasum mucosa in ruminants is Monolayer columnar epithelium , Epithelium Cells There are still a few lymphocyte and Endocrine cell 。 （1） Columnar cell , can secretion Mucus Namely surface mucous cell (surface mucouscell), the cells are columnar, nucleus It is located at the base of the cell and is oval. There are a lot of mucogen particles on the top of the cell. This Cell secretion Neutral or Weak alkalinity Mucopolysaccharide It forms a mucus layer on the surface of the mucosa to lubricate and protect the gastric mucosa. Under physiological conditions, the surface mucus cells are renewed once every 3-4 days, except bone marrow In addition, this cell updates faster than any other Histiocyte The updates are fast. （2） lymphocyte , scattered epithelial cells between. They are usually small lymphocytes, with 52.39 ± 4.59 such cells per 1000 epithelial cells. （3） Gastric fovea (Gastric pit) is the formation of epithelial depression on the mucosal surface. The average diameter of gastric pits in human stomach is 70 μm , 200 μ m in length pylorus The gland area is the deepest, the distance between adjacent gastric pits is about 0.1 mm, and there are often several at the bottom of each gastric pit gastric gland The opening of. Inherent layer
The lamina propria is occupied by a large number of gastric glands, with a small amount of connective tissue (Mainly Reticular fibre ）It constitutes its support, and also contains blood capillary , scattered smooth muscle 、 Fibroblast 、 Eosinophils And a small amount of plasma cells and mast cells There are a few lymphocytes and isolated cells around the gastric gland Lymph node Solitary lymph nodes are mainly distributed in the pyloric gland area, and pig There is a large amount of infiltrating white blood cell And lymph nodes. According to the different distribution and tissue structure of gastric glands, the gastric glands are divided into cardia Glandular area Fundus gland of stomach Area and pyloric gland area. (1) The cardiac gland area is located in the annular stenosis area around the cardia. However, the cardiac gland area of pig stomach can account for about 1/2 of the whole stomach. Glandular area Glands Short, branching tubular gland, with a small amount between gland cells Endocrine cell and Parietal cell 。 (2) The fundus gland area is a single tubular gland or a branched tubular gland located at the bottom of the stomach. The fundus gland area of all ruminants is very developed. The fundus gland area of carnivores occupies more than 1/2 of the whole stomach, horse More than 1/3 of the stomach. Nearly 1/4 of the pig stomach is the fundus gland area, and 2/3 of the abomasum in ruminants is the fundus gland area. Glands can be divided into neck, body and bottom Main cell , parietal cells, neck Mucous cell Endocrine cells and undifferentiated cells. The chief cell, also known as gastric enzyme cell, is distributed in the body and bottom of the gastric fundus gland. The cells are cubic or columnar, with round nuclei near the cell base; Top of cytoplasm is full enzyme Original particles, light staining, base Basophil 。 Electron microscope The cell base has developed Rough endoplasmic reticulum , there are abundant Golgi complex A large number of round zymogen particles; The zymogen particles are generally large, electron density No, outsourcing has plasma membrane 。 Parietal cell, also known as hydrochloric acid cell and oxynic cell, mainly secretes hydrochloric acid and Internal factor 。 The cells are round or cone shaped, with round nuclei and double nuclei, which are located in the center of the cells; Cytoplasm Strongly acidophilic. Under the electron microscope, the cytoplasm contains abundant mitochondrion , Golgi complex and Smooth endoplasmic reticulum Tubular vesicle system; The free side of the cell is concave inside the cell, forming many circuitous and branching tubules, which are called intracellular secretory can aliculus. The number of mucus neck cells is small and located between parietal cells. The cells are short columnar or cuboidal, with flat nuclei, located at the base of the cells, and the cells can secrete acidic mucus. In addition, the cervical mucus cells may be able to differentiate into other cells of the fundus gland.
Endocrine cells are scattered among several other gland cells. Because the cytoplasm base of the cell contains rich secretory granules, it can also be called a base Granulosa cell （basalgranular cell）。 The endocrine cells in the stomach mainly include D, G, EC and ECL cells, which can promote or inhibit the digestive function of the stomach. Undifferentiated cells stem cells (stem cell) is distributed between the neck of gastric fundus gland and the bottom of gastric pit, and can differentiate into other cells of gastric fundus gland. (3) The pyloric gland area is located in the pylorus. Almost 1/2 of the stomach of carnivores is the pyloric gland area, but the abomasum of ruminants and the pyloric gland area of the stomach of horses occupy 1/3, and the pyloric gland area of pigs only occupies about 1/4 of the stomach; The pyloric gland of the human stomach accounts for about 1/5 of the gastric mucosa. The boundary between the pyloric gland area and the fundus gland area is not obvious. There is a transitional zone with a width of several millimeters between the two gland areas, which is called intermediate gland.
dog The middle gland of the stomach is very developed. The gastric pit in the pyloric gland area is deep and the lumen is large, some of which can reach 1/2 of the gastric gland, Glandular cell by Mucous gland , secreting mucus, columnar glandular cells, oblate nuclei at the base of cells, and Mucin grain, HE staining Light; There are a few parietal cells and endocrine cells between glandular cells. The pyloric gland is a branch coiled Tubular gland, which secretes mucus with high consistency, some scholars believe that it also contains less Pepsinogen 。 In addition, the pyloric gland also contains a large amount of G cell , Secretion gastrin (Gastrin), promoting organism gastric acid It can enhance the digestive function of the stomach. Mucosal muscularis
It is composed of two thin layers of smooth muscle, the inner ring and the outer longitudinal, with a little inner muscle fibers It enters the lamina propria and penetrates around the glandular ducts. The contraction of these smooth muscles is conducive to the secretion of gastric glands and promotes the digestion of the stomach. The submucosa is composed of developed Loose connective tissue Composition, which contains rich nerve 、 blood vessel and lymph gland 。 pig cardia and pylorus There are also Lymph node 。 Gastric wall The muscular layer is thick and consists of three layers smooth muscle The group consists of internal oblique muscle, middle ring muscle and external longitudinal muscle. The internal oblique muscle and the middle circular muscle cardia Ministry and pylorus Thickening of the cardia physiological sphincter , on Pyloric part Form pyloric sphincter. The external longitudinal muscle in the greater curvature of stomach and Curvature of stomach It is relatively developed. The motor function of the stomach is mainly controlled by the gastric muscle layer. The circular and longitudinal muscle layers are connective tissue Connected, which contains intermuscular Plexus 。 stomach Serous membrane from Loose connective tissue Composition, which also contains rich vertical nerve 、 blood vessel and lymph gland 。 
