islets of Langerhans

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Related to Pancreatic islets: pancreas, islets of Langerhans, insulin

islets of Langerhans:

see pancreaspancreas
, glandular organ that secretes digestive enzymes and hormones. In humans, the pancreas is a yellowish organ about 7 in. (17.8 cm) long and 1.5 in. (3.8 cm) wide. It lies beneath the stomach and is connected to the small intestine at the duodenum (see digestive system).
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Islets of Langerhans

 

the groups of cells in the pancreas of man and vertebrates (except cyclostomes) that form the endocrine part of the organ, secreting the hormones insulin and glucagon into the blood.

The islets of Langerhans are named for the German scientist P. Langerhans, who described them in 1869. In 1901, the Russian scientist L. V. Sobolev proved their endocrine function and established the occurrence of changes in the islets with diabetes mellitus. The dimensions of the islets of Langerhans are 50 to 500 microns, and there are between ten and 20 islets per mg of gland tissue. The islets do not communicate with the gland’s effluent ducts.

The islets of Langerhans develop from tubular processes of the anterior gut and, depending on the type of animal, consist of cells of several types. All animals have α cells and β cells. The granules of α cells are considered to be a form of glucagon deposit; the β cells, of insulin. C cells and D cells (the former have been found in the islets of Langerhans of guinea pigs; the latter, in man and dogs), which lack granules, are converted to α cells and β cells. In all, the tissue of the islets of Langerhans makes up 0.9 to 3.6 percent of the mass of the pancreas in children and 0.9 to 2.7 percent in adults.

V. M. SAMSONOVA

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melanogaster and Zebrafish), to delicate large cells or cell clusters (adipocytes, embryoid bodies, pancreatic islets, duct cells and hepatocytes), to seeds (Arabidopsis) and beads (cells growing in or on beads, combi-chem libraries and bead-based assays).
RAMAN SPECTROSCOPIC ANALYSIS OF PANCREATIC ISLETS Kimberly Hobbs, Emanuel Waddell, Adriel D.
cells in human mature pancreatic islets and express insulin in a glucose-concentration dependent manner, and enables the easy obtainment of the number of cells which meets the demand.