Background: The pancreas is an accessory organ of the digestive system and also an important endocrine organ of vertebrates that produce and release substances in the body. The pancreas has both endocrine and exocrine function. Its endocrine function is to regulate blood sugar levels by secretion of hormones like insulin, glucagon, stomatostatin and pancreatic polypeptide and an exocrine function that helps in digestion. The study was performed to document the ultrastructural details of pancreas of guinea pigs by scanning and transmission electron microscopy.&nbsp;&nbsp; 
 
Methods: 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 according to standard operating procedure by using the Carbon dioxide asphyxiations as per CPCSEA norms and pancreatic pieces were utilised for SEM and TEM study.&nbsp; 
 
Result: Pancreas was irregular in shaped and showed splenic, ventricular and intestinal lobes. In SEM, the parenchyma was covered by the dense irregular capsule. Each lobule contained many acini which were connected by a thin, long duct with branched pattern arrangement with increasing wall thickness and diameter. In TEM, the pancreatic tissue consisted of glandular lobules comprised of acini, islets of Langerhans and connective tissue between the lobules. Numerous mitochondria and golgi complexes were also present in the acinar cell cytoplasm along with zymogen granules and rough endoplasmic reticulum. The centroacinar cells were also found. A special type of interstitial cell named telocytes and each was found with many telopodes in the exocrine part of pancreatic parenchyma. Among the four islet cell types, alpha and beta cells could be identified.&nbsp;

Ultrastructural Architecture Studies of Pancreas in Guinea pig