the pancreas is a large gland that has both exocrine and endocrine functions the majority of the pancreas consists of exocrine glands that produce about 1.5 L of alkaline digestive enzymes daily which is secreted directly into the dadum the pancreas also contains small Endocrine cells found in clusters called eyelets of langerhans which typically stain lighter than the pancreatic tissue around it the pancreas has a thin coll aous capsule that surrounds the entire pancreas although only portions of it can be seen in this image the capsule also extends into the pancreas as SEPTA forming lobules this section of the pancreas was prepared with aen stain which stains collagen a bluish purple color in order to highlight structures like the capsule SEPTA as well as the connective tissue that surrounds large blood vessels Asen stain will also stain the connective tissue surrounding the interlobular ducts a similar color as well but these ducts can be different differentiated from the blood vessels by the presence of digestive enzymes instead of red blood cells within their Lumen as well as their distinct epithelium that lines the Lumen the epithelium consists of simple columnar cells in this image but some ducts might also consist of stratified columnar or stratified cuboidal epithelium instead to the right of the intralobular ducts is the osy the adipocytes actually increase in number within the pancreas as individual's age which is a normal finding that's caused by pancreatic atrophy over time the main functional tissue of the pancreas is called the pinka if we take a closer look at this slide stain with hematoxilin and eosin or h& for short we can see that the majority of the pinka consists of the exocrine portion of the pancreas the exocrine secretory cells are arranged in groups that resemble a berry surrounding a central lumen in Latin Asin means berries which is why the groups of exocrine cells are called Asin we can see that the secretory cells are pyramid shaped and their nuclei are found slightly closer to their bases this particular slide was stained with h& which allows us to see the purple basophilic rough endoplasmic reticulum seen closer to the base of each secretory cell and the pink eosinophilic secretory granules at the apices are inactivated enzymes called zymogens in acute pancreatitis it's the exocrine secretory cells that are damaged and end up releasing their enzymes into the immediate surroundings these strong digestive enzymes cause additional damage to the pancreatic tissue that leads to severe inflammation as well the center of the Asen will sometimes contain one or more cells with a paler appearance these cells are called Centro asinar cells and they're actually extensions of the small ducts that drain the digestive enzymes produced by the asinai called intercalated ducts the presence of Centro asinar cells is a unique feature of the exocrine pancreas and is also an identifying marker that indicates the beginning of the intercalated ducts these ducts are lined by simple cuboidal epithelium in can be seen in this image as a linear arrangement of cuboidal cells and in this cross-section of the intercalated duct you can see the circular duct that's formed by the cuboidal cells the intercalated ducts then drain into slightly larger intralobular ducts like the one here as the ducts progress they gradually increase in diameter and the connected tissue surrounding these ducts also thickens the epithelium will also transition from simple cuboidal cells to stratified cuboidal cells the inal lobular ducts then drain into the interlobular ducts which are located between the lobes but within the SEPTA these ducts are lined with epithelium that can be simple columnar stratified columnar or stratified cuboidal epithelium and have a very thick layer of connective tissue surrounding them the interlobular ducts eventually join with a large main pancreatic duct which runs the length of the pancreas and leads to the common bile duct in order to drain into the dadum a smaller accessory duct is also often present which also drains into the dadum let's move on to the endocrine portion of the pancreas which forms clusters of paler cells such as the one seen in this image called eyelets of langerhans the overall size of the eyelets can vary but they can be identified pretty easily by their lighter stain in smaller cells when compared to the surrounding exocrine tissue when we increase the magnification to 20x we see that the fenestrated are perforated capillaries within the eyelets as well the eyelets of langerhans consist of four main types of cells but they cannot be easily distinguished from one another on slides stained with h& beta cells are the most common cell type which comprises approximately 70% of pancreatic eyelets and secrete insulin the eyelets also consist of alpha cells that secrete glucagon Delta cells that secrete somatostatin and PP cells that secrete pancreatic polypeptide this image of an eyelet was stained with gamori stain which allows us to differentiate the beta cells that stain bluish purple and the alpha cells that stain pink and we can also see just how much of the iset is made of beta cells in individuals with type 1 diabetes there'll be a decreased number of beta cells as a result of autoimmune destruction of these cells specifically all right as a quick recap the pancreas has both exocrine and endocrine functions as and I are the berry-shaped groups of exocrine cells that secrete digestive enzymes the individual secretory cells are pyramid shaped with basophilic rough endoplasmic reticulum and nuclei at their base and eosinophilic granules at the Apex eyelets of Langer hands are responsible for the pancreas is endocrine secretion and are seen with h& by their paler stain and smaller cells when compared to the surrounding tissue the eyelets consist of Alpha Beta Delta and PP cells with beta cells making up about 70% of the eyelets helping current 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