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Definition / general | Microscopic (histologic) images | Positive stains | Electron microscopy imagesCite this page: Jain D. Endocrine pancreas. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/pancreasendocrine.html. Accessed February 18th, 2019.
Definition / general
- Consists of islets of Langerhans, represents 1% of pancreas (percentage higher at birth)
- Round, compact, highly vascularized with scanty connective tissue
- More irregular outline and trabecular arrangement in posterior head of pancreas with cells producing pancreatic polypeptide
- Size of islets usually 0.1 to 0.2 mm, endodermal origin, one million islets present in pancreas
- Islet composition: beta cells (68%), alpha cells (20%), delta cells (10%), PP cells (2%), serotonin cells (rare)
- Postgastrectomy, may get islet hypertrophy, then beta cell proliferation, then atrophy and amylin deposits (Hum Pathol 2000;31:1368)
- Alpha cells: produce glucagon; peripherally dense and round on EM
- Beta cells: produce insulin and islet cell amyloid polypeptide (amylin), crystalline appearance on EM with surrounding halo
- Delta cells: produce somatostatin (represses release of insulin and glucagon), large pale granules on EM
- D1 cells: produce vasoactive intestinal polypeptide (VIP), which induces glycogenolysis and hyperglycemia, stimulates GI fluid secretion and causes secretory diarrhea
- Enterochromaffin cells: synthesize serotonin, produce carcinoid syndrome
- Gastrin cells: pancreas usually lacks gastrin producing cells, although gastrinomas are common
- PP cells: produce pancreatic polypeptide, which stimulates secretion of gastric and intestinal enzymes and inhibits intestinal motility; present in islets and scattered in exocrine pancreas; more PP cells in posterior head of pancreas (from ventral bud)
- Nesidioblastosis: islets in intimate association with ducts with formation of ductuloinsular complexes
- Nesidiodysplasia: loss of the usual centrilobular concentration of larger islets, with increased small irregularly distributed aggregates of islet cells; also increase in beta cell nuclear size and DNA content; may be associated with endocrine neoplasms (Hum Pathol 1988;19:1215)
- Peliosis: selective congestion and dilation of vessels of islets only, not seen in vessels elsewhere
Microscopic (histologic) images
AFIP
Islets in newborn
Adult pancreas - ordinary type islet
Adult pancreas - irregular type islet
Adult pancreas: distribution of islet cell types
Islet rich in PP cells in posterior part of pancreatic head
Islets: cells with clear cytoplasm (centroacinar and ductal cells) stand out from a background of basophilic acinar cells
Nesidioblastosis in adult with persistent adult hyperinsulinemic hypoglycemia: clustering of irregular islets in vicinity of small ductules
Contributed by Dr. Cesare Bordi
Islet hyperplasia of Beckwith-Wiedemann syndrome: note crowding without fusion of islets inside pancreatic lobules
Images hosted on other servers:
Islets: cells with clear cytoplasm (centroacinar and ductal cells) stand out from a background of basophilic acinar cells
Positive stains
Electron microscopy images
AFIP
Adult pancreatic islet cells
Images hosted on other servers:
Zymogen granules
