Pancreas in Guinea pig: Scanning and Transmission Electron microscopic Studies

The pancreas is an accessory organ of the digestive system and also an important endocrine organ of vertebrates. The pancreas has both endocrine and exocrine function. Its function is to regulate blood sugar levels by secretion of hormones like insulin, glucagon, stomatostatin and pancreatic polypeptide. Six adult healthy guinea pigs of 16 -32 weeks of age (Irrespective of sex) were procured from the Department of Laboratory Animal Medicine, TANUVAS as per ethical committee approval. Animals were dissected as per CPCSEA norms and pancreatic pieces were utilised for SEM and TEM study. The study was performed to document the ultrastructural details of pancreas of guinea pigs by scanning and transmission electron microscopy. Pancreas was irregular in shaped and showed splenic, ventricular and intestinal lobes. In SEM, the parenchyma was covered by the dense irregular connective tissue capsule. Each lobule contained many acini which were connected to each other by a thin, long duct with branched pattern arrangement. The acinar cells were drained by intercalated duct - interlobular duct - intercalated duct - interlobar duct - interlobular duct with increasing wall thickness and diameter. In TEM, the pancreatic tissue consisted of glandular lobules comprised of acini, islets and connective tissue between the lobules. Inside the lobules, lot of small blood vessels and blood capillaries were found surrounding the gland which contained few telocytes. Numerous mitochondria and golgi complexes were also present in the acinar cell cytoplasm along with the zymogen granules and rough endoplasmic reticulum. The 5-6 acinar cells were found surrounding the centroacinar cells which was found smaller in size when compared to the acinar cells. Many microvilli were found surrounding the cell membrane of the centroacinar cell. In the proximity to the blood capillary, a special type of interstitial cell named telocytes were found with many telopodes in the exocrine part of pancreatic parenchyma which had association with the acinar cell and blood vessel. Among the four islet cell types, alpha and beta cells could be identified in the present study. Alpha cells had irregular outline and had numerous homogenous small membrane bound granules with moderate to high electron density. Beta cells were distributed throughout the islet both in the center and periphery. The beta granules were membrane bound with an electron lucent halo around the granules. Research highlights: By SEM, the parenchyma was covered by the dense irregular connective tissue capsule. Each lobule contained many acini which were connected to each other by a thin, long duct with branched pattern arrangement. By TEM, the pancreatic tissue consisted of glandular lobules comprised of acini, islets and connective tissue between the lobules. Inside the lobules, lot of small blood vessels and blood capillaries were found surrounding the gland which contained few telocytes.