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Subject: Veterinary Anatomy × Author: RAYAZ AHMED × End date: 2013 × Start date: 2013 ×
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    ThesisItemOpen Access
    GROSS, HISTOLOGICAL AND HISTOCHEMICAL STUDIES ON THE PANCREAS OF ALBINO RAT (Rattus norvegicus)
    (SRI VENKATESWARA VETERINARY UNIVERSITY , TIRUPATI – 517502. (A.P.) INDIA, 2013-07) RAYAZ AHMED; JAGAPATHI RAMAYYA, P (Major); RAJU, N. K. B.; Suresh Kumar, R V
    ABSTRACT : The study was conducted on twelve albino rats (Rattus norvegicus). The pancreas was a diffuse lobulated gland and appeared pink in colour. The gland was divided into three parts viz., gastric, splenic and duodenal parts. The pancreas of the rat was covered by a thin capsule, made up of predominantly, collagen fibres. Each acinus showed a single row of pyramidal epithelial cells resting on the basement membrane. The cytoplasm of the acinar cells showed two distinct zones. The basal zone was dense and basophilic, while the apical region contained the numerous fine zymogen granules. Two types of acinar cells were noted in pancreas i.e active and resting type. In active cells the nucleus was spherical, euchromatic and located at the centre, whereas resting cells possessed heterochromatic nucleus and placed close to base of the cell. The duct system of the pancreas consisted of larger interlobular, medium sized intralobular and small intercalated ducts. The endocrine tissue appeared as lightly stained rounded or oval areas between the darkly stained acini. In albino rat three different types of islets were observed. They were small, medium and large islet types. The alpha and pancreatic polypeptide cells occupied the peripheral region in the islet. Whereas, beta cells were mostly present in its interior. Delta cells were distributed randomly throughout the islets and they were long, flattened, irregular in shape and characterized by the presence of small granules. The pancreatic polypeptide cells were found singly or in clusters at the periphery of the islets. The pancreas of rat was supplied by celiac and anterior mesenteric arteries. The blood capillaries in the islets had typically fenestrated endothelium walls and were greatly extended, tortuous or large in calibre as compared with the capillaries of the exocrine pancreas. The lymph vessels were present in the exocrine part, whereas the endocrine portion was devoid of lymph vessels. They were characterized by thin walls and showed fenestrated endothelial cells and devoid of pericytes. The nerve bundles were divided into several thick and thin branches and they formed nervous plexus in pancreas of rat. According to the localization in the organ, the pancreatic nervous plexus were divided in to four types viz., periacinous, periinsular, perivascular and periductal plexuses. The nerve cells were observed either as isolated cells, small ganglia or large sized ganglia in rat pancreas. The isolated nerve cells were generally present in the islets. The ganglionic cells occupied a peripheral position in the islets of Langerhans in rat. The secretory cells of the acini and the epithelial cells of the pancreatic ducts showed strong positive reaction for Periodic acid Schiff. But moderate activity was noted in islets of Langerhans in pancreas of rat. The secretory cells of the acini and islets showed moderate to strong reaction for alcian blue. Further, epithelial cells of the pancreatic ducts showed strong positive reaction for alcian blue. The islets of Langerhans showed strong positive reaction for Best’s carmine. The epithelial cells of the pancreatic ducts also showed strong positive reaction for glycogen in the present study. In rat secretory cells of acini showed mild reaction for Best’s carmine. The secretory acini showed mild reaction for bromophenol blue, whereas islets of Langerhans showed strong reaction.