The Morphological Study On The Gastrin Cells In The Gastrointestinal Tract Of Developing Mouse

Objective: To further investigate the ontogeny, distribution, morphology and the quantitative change of gastrin cells (G cells) in the gastrointestinal tract, as well as the relationship between G cells, somatostatin cells (D cells) and parietal cells in the stomach during the development of mouse gastrointestinal tract.Methods: The sections of mouse gastrointestinal tract from ED 16 to day 45 after birth were stained with irnmunohistochemical SP method to show the ontogeny, distribution and morphological charactristics of G cells and D cells in the mouse gastrointestinal tract. The ratio of G cells, D cells in the gastric antrum and the relationship of both cells with parietal cells was also studied using SP method. The distribution feature of both G and D cells were observed using immunohistochemical double staining techniques.Results: G cells could only be found in the mouse gastric antrum as early as at ED 17, and in the small intestine at ED 18. Statistics results showed that from ED 17 to ED 19, the number of G cells in the duodenum was significantly greater than that in the gastric antrum, whereas the number was lowest in the remainder of small intestine. From day 1 to day 45 after birth, the number of G cells in the gastric antrum increased continuously, and was significantly greater than that in the duodenum and the remainder of small intestine.G cells had never been found in the body of stomach and the colon in the mice before and after birth.G cells in the gastrointestinal tract were various in shape, the immunoreactive positive processes of the cells could be seen around the capillaries, extending to basement membrane, and in contact with the adjacent cells. Some processes could be seen extending to the free surface of the epithelium and secreting immunoreactive positive substance into the lumen of gastric gland or the lumen of the gastrointestinal tract, suggesting that most of them were open typed endocrine cells of gastrointestinal tract.D cells could be found in the body of the stomach as early as at ED 17, and in the gastric antrum at ED 18. From the embryonic period to the maturity, the increase in the number of the D cells was always smaller than that of G cells in gastric antrum.The ratio of G/D was about 1:1 to 4:1 before birth, but 3:1 during the newborn period and 4:1 during maturity. In stomach, most of D cells existed in the body, while G cells were only located in antrum. In antrum, D cells could be seen being adjacent to G cells in the same section with irnniunohistochemical double staining techniques. After stained with eosin, both G and D cells could be found being adjacent to parietal cells. Under the light microscope, some immunoreactive positive substance could be found around the two types of cells.Conclusion: The ontogeny of G cells in the mouse gastrointestinal tract was earlier than that in the rat. But the quantitative change and the distribution were similar to those of the rat and human fetus. The morphological evidences that extension of the immunoreactive positive processes of the cells to the free surface of the epithelium, between the adjacent other cells, or to the basement membrane and around capillaries and the immunoreactive positive substance detected in the lumen of the gastric gland and the gastrointestinal tractsuggested that G cells might possess endocrine, exocrine and paracrine functions simultaneously.The hormones released from G cells and D cells might regulate the development of the mouse gastrointestinal tract. The two types of cells coordinate in function to maintain the normal secretion of gastric acid. The roles of G and D cells in the gastrointestinal tract movement and the other physiologic activity such as digestion were discussed.