Histology & Function of The Pancreas
- 1. Cairo University Faculty of Medicine Histology Department 2013 Histology & Function of The Pancreas Candidates 1- Fatma Abdelnasser Ghoneim (768) 2- Fifi Sami (777) 3- Fatma Mahmoud Elshahed (770) 4- Fahima Elsharkawi (776)
- 2. Pancreas The pancreas is a glandular organ in the digestive system and endocrine system of vertebrates
- 3. Histology of Pancreas Under a microscope , stained sections of the pancreas reveal two different types of parenchymal tissue. Lightly staining clusters of cells are called islets of Langerhans and Darker-staining cells form acini connected to ducts . ..
- 4. The Acinus The exocrine pancreas is classified as A compound tubuloacinous gland. The cells that synthesize and secrete digestive enzymes are arranged in grape- like clusters called acini
- 5. The Acinus • LM : pyramidal cells with ill_ distinct cell boundaries. The nuclei are rounded and basal. the Cytoblasm shows basal basophilia and apical acidophilic zymogene granules. • Em : tight junctional complexes. Many rER. Intra cellular canaliculi are found between acinar cells. The golgi apparatus is supra nuclear. apical membrane_bound electron dense zymogen granules
- 6. Pancreatic Ducts • Intercalated ducts • Intralobular ducts • Interlobular ducts • Intralobar ducts • The main pancreatic duct -
- 7. Intercalated ducts Intercalated ducts receive secretions from acini. They have flattened cuboidal epithelium that extends up into the lumen of the acinus to form what are calledcentroacinar cells.
- 8. Intralobular ducts • Intralobular ducts have a classical cuboidal epithelium and, are seen within lobules. They receive secretions from intercalated ducts
- 9. • -Interlobular ducts are found between lobules. • The smaller forms have a cuboidal epithelium, while a columnar epithelium lines the larger ducts. Intralobular ducts transmit secretions from intralobular ducts to interlober ducts. Interlobular ducts
- 10. Interlobar ducts transmit secretions from interlobular ducts to the major pancreatic duct.The main pancreatic duct received secretion from interlobular ducts and penetrates through the wall of the duodenum. In some species, including man, the pancreatic duct joins the bile duct prior to entering the intestine.
- 11. Islets of Langerhans • They are multiple pale areas scattered between the darkly stained pancreatic acini. They present at the tail region in number about one million. They are surrounded with delicate reticular fibers but not capsulated
- 12. Cell types • (1) Alpha cells producing glucagon (15–20% of total islet cells) • (2) Beta cells producing insulin and amylin (65– 80%) • (3) Delta cells producing somatostatin (3–10%) • (4) Epsilon cells producing ghrelin (<1%) • (5) PP cells (gamma cells) producing pancreatic polypeptide(3–5%) • (6) C_cells may represent immature or degenerated cells (3%) • (7) G_cells secrete gastrin • (8)Ganglion cells aggregated nerve cells,for autonomic nervous control of the islets
- 13. Paracrine feedback * Insulin: activates beta cells and inhibits alpha cells. * Glucagon: activates alpha cells which activates beta cells and delta cells. * Somatostatin: inhibits alpha cells and beta cell
- 14. Function of pancreas (1) Endocrine islets of Langerhans cells secrete hormones that pass to the blood as: α cells secrete glucagon, β cells secrete insulin, δ cells secrete somatostatin, and PP cells secrete pancreatic polypeptide (2) Exocrine The acinar cells produce digestive enzymes and an alkaline fluid in response to the small intestine hormones secretin and cholecystokinin include trypsin, chymotrypsin, pancreatic lipase, and pancreatic amylase
- 15. Regulation • Sympathetic (adrenergic) α2: decreases secretion from beta cells, increases secretion from alpha cells • Parasympathetic (muscarinic) M3 increases stimulation from alpha cells and beta cell
- 16. Diseases • Diabetes, type 1 • Diabetes, type 2 • Cystic fibrosis • Pancreatic cancer • Pancreatitis • Pancreatic pseudocyst • Islet cell tumor • Enlarged pancreas