| It was indicated that the pancreatic islets is composed of no less than 4 types as A, B, D and PP neuroendocrine cells, synthesize and release separately to monoamine substance and polypeptide hormones as glucagon, insulin, somatostatin and pancreatic polypeptide, by immunohistochemical and immunocytochemical studies. The 4 type cells and their hormones influence each other, regulate mainly to metabolism of the substances as glucose.The polypeptide hormones or secretory granules produced from the endocrine cells of pancreatic islets were released as exocytosis into the interstitial fluid of pancreatic connective tissue space, absorbed immediately into blood capillaries, transport and play to action passing through the hepatic portal venous route.Be worth to point out, the lymphatic vessels as well as blood vessels exist around the endocrine cells of pancreatic islets; the diameter and penetrate of lymphatic capillaries are large so far as those of blood capillaries. Why macromolecular polypeptide hormones or secretory granules get into hepatic portal vein not into lymphatic vessels? Whether or not newborn polypeptide hormones as insulin passing liver is damaged or destroyed? Therefore, it is encouraged that to re-explore or clarify thereleasing form and extracelullar transporting route or rule of polypeptide hormones as insulin or secretory granules of the endocrine cells of pancreatic islets, and the relationship with pathogenous mechanism of type 2 diabetes mellitus.Part one: Fine and Ultra-architecture and Its Significance of the Connective Tissue Fibers in Human Pancreas: An Observation with NaOH- Maceration / SEM-Method.Objective: To explore the fine and ultra-architecture and its significance of the connective tissue fibers in human pancreas.Methods: Using the technique with NaOH- maceration and ultrasonic wave (USW) cleaning, human pancreatic specimens keeping only connective tissue fibers were observed and analyzed by scanning electron microscope (SEM).Results: After the pancreatic tissue treated with NaOH-maceration and USW cleaning, its cellular elements and basic substance were macerated completely and only connective tissue fibers still preserved a primary architectural feature. The outlines of pancreatic lobules, interlobular connective tissue and pancreatic islets were clearly seen. The pancreatic ducts, arteries and veins, lymphatic vessels and nerve fiber bundle were easily recognized and demarcated. The bundle or network woven by the connective tissue fibers was all composed of a 10-100 nanometre fibrils accumulated by collagenous protein, or briefly called as collagenous fibrils.Conclusion: The fibrous network of pancreatic connective tissue in vivo was full with tissue fluid, framed the tissue skeleton and channel for this organ, and provided a suitable microenvironment for support and protection, nutrition andmetabolism, secretion and communication, reproduction and restoration of the pancreatic endocrine and exocrine cells.Part two: The structural feature of pancreatic tissue indicated normal transporting for polypeptide insulin passing through lymphatic not portal vessel route.Objective: To explore the structural foundations of releasing pattern and extracellular normal transport route of polypeptide hormones of pancreatic islets.Methods: The normal tissue of the rat and human pancreatic tails were observed by light and transmission electron microscope (LM/TEM).Results: The pancreatic tissue is chiefly compared of glandular lobules formed with acinus and connective tissue separating these lobules. Pancreatic ducts, blood and lymphatic vessels, myelinated and unmyelinated nerve fibers, passed within connective tissue. 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.Conclusion: The structural features of pancreatic tissue suggest that the releasing pattern of polypeptide hormones of pancreatic is...
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