Cholecystokinin And Pancreatic Polypeptide Immunoreactive Cells In The Gastrointestinal Tract And Pancreas Of Developing Mouse

Objective: To observe the ontogeny, distribution, morphology and the quantitative change of cholecystokinin(CCK) and pancreatic polypeptide(PP) immunoreactive (IR) cells in the gastrointestinal tract and pancreas during the development of mouse.Methods: The sections of mouse gastrointestinal tract and pancreas from ED 12 to day 45 after birth were stained with immunohistochemical SP method to show the ontogeny, distribution and morphological characteristics of CCK-IR cells and PP-IR cells.Results: CCK-IR cells could be found in the mouse small intestine as early as ED 16, and in the colon at ED 19. Single CCK-IR cells could only be found in the body of stomach at ED 18, ED19, and never been found after birth; CCK-IR cells had never been found in the gastric antrum in the mice before and after birth. In pancreas CCK-IR cells could be found as early as ED12.CCK-IR cells were scattered in the villi of small intestine from ED16 to ED19. After birth, they could be seen in the villi and in the intestinal glands. In colon, CCK-IR cells were located both in the epithelium of mucosa and in the glands. In pancreas, CCK-IR cells were predominantly located in the islet, the cells staining varied from strong positive to weak; sometimes single CCK-IR cell of strong positive stained could also be seen in the acinar region and embedded among the epithelial cells of pancreatic ducts.Statistics results showed that: from ED16 to ED 19, the number of CCK-IR cells in the small intestine increased continuously, and showed a peak at day 30 after birth, but decreased obviously at day 45. At day 1, 7 and 15 after birth, the number of CCK-IR cells in ileum was significantly greater than that in the duodenum and jejunum. During the embryonic period, single CCK-IR cell could be seen in the colon. From day 1 to day 30 after birth, the number of CCK-IR cells increased continuously, and then decreased obviously at day 45. The number of CCK-IR cells in pancreas showed a peak at ED 15 before birth, and then decreased gradually. After birth only a few CCK-IR cells could be seen.PP-IR cells were first detected in the mouse pancreas as early as ED17, and in the colon at ED 18. After birth to the maturity, PP-IR cells could be found both in the pancreas and the colon, but not in the body of stomach, the gastric antrum and small intestine. During the development of the pancreas, PP-IR cells were located in the periphery of the islet and scattered among the epithelial cells of pancreatic ducts. Statistics results showed that from ED 17 to day 15 after birth, the number of PP-IR cells increased gradually, and showed a peak at day 15. During ED 18 to day45 after birth of colon, PP-IR cells could always be found in the epithelium of glands. At day 30 after birth, the number of PP-IR cells was greater than that of the other age groups.CCK-IR cells and PP-IR cells in the mouse gastrointestinal tract and pancreas were various in the shape, the immunoreactive positive processes of the cells could be seen extending between the adjacent cells. The positive staining cells in the pancreas varied from strong positive to weak.Conclusion: From embryonic period to day 30 after birth, the number of CCK-IR cells in the small intestine and the colon increased continuously, and the hormone released from CCK-IR cells might promote the development of the small intestine and the colon. The change that the number of CCK-IR cells in development pancreas suggests that major function of CCK expressed in the pancreas might stimulate the growth and differentiation of pancreas.The distribution of PP-IR cells in the developing mouse pancreas and other organs were different from human and the other species; the change that the number of PP-IR cells in pancreas and colon suggest that pancreatic polypeptide might regulate the activities of the pancreas and the colon.Some immunoreactive positive processes extending between the adjacent cells of CCK-IR cells and PP-IR cells could be seen, and the immunoreactive positive material could also be found round the cells. It suggests that both endocrine cells might influence the functions of adjacent cells mediated by paracrine.