Pancreas - Overview

Click on images for full-size photographs

The pancreas is a fatty-looking organ that is located in the mesenteries between stomach, duodenum, and ascending and transverse colons. The pancreas does not have a connective tissue capsule but is covered by loose vascular connective tissue of the mesenteries. Connective tissue septa divide the pancreas into lobes and lobules. The pancreas contains both exocrine (serous acini) and endocrine (islets of Langerhans) components. The acini have a small lumen and consist of secretory cells that have basophilic cytoplasm in their basal region and eosinophilic cytoplasm containing secretory granules in their apical region. The acini connect to individual intercalated ducts, which join to form larger intralobular ducts. These drain into interlobular ducts, which empty into the main excretory ducts. One or more of these pancreatic ducts extend to the duodenal papilla. The smaller ducts are lined by cuboidal epithelium, the larger ducts by columnar epithelium. Accessory splenic tissue may be found in the pancreas.

The 4X micrograph depicts a pancreas separated into lobules by septa. The 10X and 20X micrographs present details of the acini of the exocrine pancreas as well as a duct. The 40X micrograph shows the basal basophilic and the apical eosinophilic cytoplasm with secretory granules of the secretory acinar cells. An islet of Langerhans is also visible in the 40X micrograph (Islets of Langerhans are depicted more extensively in Chapter 8. Endocrine organs, Pancreas).