The Endocrine Pancreas


  • The endocrine portion of the pancreas consists of numerous small clusters of cells called islets of Langerhans or, more simply, islets. Humans have roughly one million islets.

  • These islets contain three major cell types, each of which produces a different hormone:

  • Alpha cells (A cells) secrete the hormone glucagon.

  • Beta cells (B cells) produce insulin and are the most abundant of the islet cells.

  • Delta cells (D cells) secrete the hormone somatostatin, which is also produced by a number of other endocrine cells in the body.

  • Islets are richly vascularized - though comprising only 1-2% of the mass of the pancreas, they receive about 10 to 15% of the pancreatic blood flow.

  • They are also innervated by parasympathetic and sympathetic neurons, and nervous signalscan modulate the secretion of both insulin and glucagon.