ABSTRACT
In the present study, the postanatal developmend, microvascular and innervation of both indocrine and exocrine parts of the pancreas was done on 180 albino rats of Spargue-Dawley strain of both sexes. 30 animals were adults [60 days-old] while the remaining 150 animals were divided into five groups each consisted of 30 animals of 1, 7, 14, 21 and 28 days old respectively, and it was observed that: * Exocrine part of the pancreas had different rate of growth than the endocrine part, it was found that in the first 7 days of life the endocrine tissue grows faster than the exocrine tissue, then after that age the exocrine tissues strated to grow rapildy with rate more than that of the endocrine tissues up of age of 28 days, after this age onwards both endocrine and exocrine parts showe constant and slow rate of growth. * The body weight and pancreatic weight were found to increase with increasing age, the rate of growth was rapid during the first week after birth with more increase in body weight than pancreatic weight, after 28 days the rate of growth of both body and pancreas was more slower and both increased nearly propartionally. * The total number of islets per pancreas was found to increase with increasing age up to adulthood, the rate of increase was rapid in the first 28 days of life then became slower after that age. * In one day old rats, it was found the presence of distinct blood supply for exocrine part of the pancreas as well as the endocrine part, small and few glomerular like swellings and insulo-acinar capillaries were detected in this age group. The insular capillaries appear to have the same caliber as that of the acinar capillaries with increasing age of the animal all blood vessels of the pacnreas including intrlobular arteris, intralobular arteries as well as insular and acinar capillaries appeared to increase in size. Also the size and frequency of intra-insular capillaries, glomerular like swellings and insulo-acinar portal vessels were increased with increasing age up to adulthood. * True and pseudocholinesterase positive interlobular nerve trunks were observed to divide repeatedly forming the intrapancreatic nerve plexues [peri-acinar, peri-insular, intrainsular, periductal and peri-vascular nerve plexuses]. All these intrapancreatic nerve plexuses were oberved from the the first week birth up to adulthood, while only scattered nerve fibers without forming nerve plexuses were noticed at one day after birth. * True and pseudocholinesterase positive intrapanceratic genglia and nerve cells were found mostly in the interlobular connective tissue septa, however some ganglia were observed among the aini, adjacent to the main pancreatic ducts and blood vessels and less commonly adjacent to islets of langehans. Succinic dehydrogenase enzyme activity was observed throught the pancreas, the exocrine part had higher enzyme reaction than that of the islets of Langerhans moreover the beta-cells showed higher enzyme activity than the cells of the periphery of the islet [A-cell region] and some A-cells possessed low or no enzyme activity at all. Connective tissue cells had low enzyme activity. The intensity of succinic dehydrogenase enzyme reaction was observed to increase with advanced age throughout the whole pancrease