Immunohistochemical Studies On The Development Of The Digestive System's Endocrine Cells In Alligator Sinensis Embryos

The digestive tract of animal was not only the important digestive organ but also the biggest endocrine organ which, with a great number of endocrine cells, played an important role in eating, digestion and other physiological activities, and might have regulation effect on the development and differentiation of digestive system of animals. Many studies on endocrine cells in digestive system of mammal and human beings embryos had been carried out but few on lower vertebral animals. Alligator sinensis, a kind of superior reptiles, acted as an important role in the course of vertebral animal evolution. Studies on the development of the endocrine cells of its digestive system would provide us with significant documents for investigating the developmental characteristics of its endocrine cells and the evolution relationship between different groups of vertebral animals. The results are as follows.The endocrine cells in the digestive and glands of Alligator sinensis embryos aged from 8th to 55th day were localized and compared by using immunohistochemical method with thirteen kinds of antiseras of hormone. During the development of pancreas in Alligator sinensis embryos, somatostatin(SS) immunoreactive(IR)cells, 5-hydroxytryptamine(5-HT)-IR cells, glucagon(GLU)-IR cells, epidermal growth factor(EGF)-IR cells appeared on 18th day. No P53 protein-IR cell, gastrin-IR cell, testosterone-IR cell, chromogranin A-IR cell, vasoactive intestinal polypeptide-IR cell, epithelial membrane antigen-IR cell or insulin-IR cell was found in the pancreas of Alligator sinensis embryos.There was some difference between Alligator sinensis and Alligator mississippiensis in the development of the pancreas1 endocrine cells. For example, Pancreatic polypeptide-IR cells appeared earlier in Alligator sinensis than in Alligator mississippiensis. In addition, somatostatin-IR cells were the most of allIR-cells in Alligator mississippiensis before hatching, but in Alligator sinensis it were glucagon-IR cells. All endocrine cells in the pancreas of Alligator sinensis embryos distributed separately in the early days. But a few gathered together from the midterm of development toward hatching stage.During the development of liver in Alligator sinensis embryos, SS-IR cells appeared in a few of sinusoid endothelial cells on 8th day. 5-HT-IR blood cells and TGF P 1-IR blood cells were found in vein vessel from 30-55th day. EGF-IR cells and SP-IR cells appeared in the outer membrane of liver from 40-55th day. And AFP-IR cells appeared in the outer membrane of liver or blood vessel endothelial neared the outer membrane only on 55th day. SS,5-HT,GLU,PP,SP,EGF and AFP were not expressed in all liver cells.SS-IR cells, 5-HT-IR cells, PP-IR cells, TGF P 1-IR cells and SP-IR cells were found in the esophagus, the stomach and the duodenum of Alligator sinensis embryos. In addition, the stomach contained GLU-IR cellsN GAS-IR cells and VIP-IR cells, and the duodenum contained GLU-IR cells and Gas-IR cells. Different endocrine cells varied from one to another in the distribution pattern, the stage of appearance and the number. No GLU-IR cell, GAS-IR cell or VIP-IR cell was found in the oesophagus and no VIP-IR cell in the duodenum. In addition, insulin-IR cell, chromogranin-A-IR cell, testosterone-IR cell and epithelial membrane antigen-IR cell were not detected in the digestive tract of Alligator sinensis embryos.The kinds and the numbers of endocrine cells in the digestive tract and glands were less at early prenatal stages but increased greatly in the midterm of development.In the digestive tract of last prenatal stages, it was stomach that had the most endocrine cells and might play the most important role in regulating the growth and differentiation of the digestive tract, the duodenum was in the second place. There were some differences between pre-natal and post-natal stages in the kinds and the numbers of the endocrine cells. With GLU-IR cells, PP-IR cells and SP-IR cells, the digestive tract of prenatal stages had different location o...