The Investigation Of Structural Foundations For The Releasing Pattern And Transport Route Of Polypeptide Hormones Released By Pancreas Islet

Objective: To explore the structural foundations of releasing pattern and extra-cellular normal transport route of polypeptide hormones of pancreatic islets.Methods: We observed normal pancreatic constitution structure with HE stain, giving us some help for the subsequence experiments. The frozen sections of pancreatic tissue, which has been injected with immuno-gold marking exogenous insulin (IGMEI), were also observed by scanning electron microscope (SEM) for the secondary and backscattered electron images (SEI/BEI). In doing so, we want to tract the transport route of insulin which has been injected into the interspace of the pancreatic tissue by modeling the route of insulin in normal physical conditions. Results: The SEI-SEM observation of the pancreatic sections revealed that the pancreatic lobules and interlobular connective tissue, blood and lymphatic vessel, pancreatic ducts and islets, and their structural feature were clearly indentified. According to whether or not it exist blood cellsand the structural feature of endothelial cells, can be distinguished between lymphatic and blood vessels. The BEI-SEM observation indicated that the stronger BEI present in pancreatic connective tissue space, lymphatic vessels or capillaries. However, weaker BEI appears in pancreatic blood vessel or capillaries. Under the TEM field, the secretory granules (200~500nm) wrapped with membrane were also seen in the connective tissue space around pancreatic islet cells. The blood capillary in pancreas is fenestrated (50nm) type.Conclusions: The results made it clear that the releasing pattern of polypeptide hormones of pancreatic islets can be a whole-releasing together with granular membrane not exocytosis as considered from traditional ideas. The polypeptide insulin or secretory granule released into pancreatic tissue fluid be rather easy entering into lymphatic duct of pancreas than into blood of hepatic portal vein.Key words: pancreas;pancreatic islet;polypeptide hormone;releasing pattern;transport route;SEM/TEM...