study of histochemical and histological structure on the pancreas of albino rat

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

Effect of predegenerated nerve grafts on axonal regeneration in the peripheral nervous system

This project has provided a general stereological survey for the study of the influence of the predegenerated nerve graft and prelesioned host site on axonal regeneration and remyelination in the peripheral nervous system. Right sciatic nerve of adult rats was sectioned at mid-thigh level, and the distal portion was allowed to predegenerate for 0, 6 and 12 days. The distal nerve segment [10-15 mm] was grafted onto the proximal nerve stump which had received a conditioning lesion 0, 6 or 12 days previously, resulting in different 9 donor-host combinations. The morphological study of the grafts was assessed 8 and/or 24 weeks after grafting. The number of regenerated remyelinated axons was counted by using a recent stereological technique. The grafts given eight weeks postgrafting had many regenerated myeflinated axons ranging from 11,000 to 28,000 axons, and the grafts given a 24 weeks postgrafting had large numbers of regenerated myelinated axons ranging from 15,000 to 29,000 axons. These results indicate that both a conditioning lesion of the host and the degree of predegeneration of the nerve graft are important in the influencing of the degree of axonal regeneration and remyelination. Six days post-lesion host is the best time which can enhance axonal regeneration before grafting. Using the retrograde tracer [Fast-Blue] for labeling the nerve cell bodies in DRG and anterior horn of the spinal cord at the levels of L[4] and L[5], the results showed there was no relationship between the number of regenerated axons and the number of the labeled nerve cells. Our results concluded the importance of neuronal vasculature in the process of axonal regeneration. Finally, we can fairly apply clinically the use of predegenerated nerve grafts and prelesioned host site in peripheral nerve repair following injury