islets of Langerhans

group of cells in the pancreas that secrete insulin

clusters of glucagon- and insulin-secreting endocrine cells in the pancreas (Anatomy)

The endocrine (i.e., hormone-producing) cells of the pancreas are grouped in the islets of Langerhans. Discovered in 1869 by the German pathological anatomist Paul Langerhans, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas. There are about one million islets in a healthy adult human pancreas, which are distributed evenly throughout the organ, and their combined weight is 1 to 1.5 grams.
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Islets of Langerhans pl.n. Irregular clusters of endocrine cells scattered throughout the tissue of the pancreas that secrete insulin and glucagon. [more]Islets of Langerhans - Community and Resources

Noun
1. cell clusters in the pancreas that form the endocrine part of that organ; secrete insulin and other hormones
(synonym) islands of Langerhans, isles of Langerhans
(hypernym) endocrine gland, endocrine, ductless gland
(part-holonym) pancreas

Insulin-producing tissue in the pancreas.