islets of Langerhans

(redirected from islet tissue)
Also found in: Dictionary, Thesaurus, Medical.

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).
..... Click the link for more information.
.

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

References in periodicals archive ?
Intercalated ducts were present close to developing islet tissue in the twenty specimens of groups A and B and not present in group C.
The observation that the preventive action of BE is not due to a blood glucose lowering effect of BE as such finds its equivalent in the results of histological studies with islet tissue.
Due to this is increased the total mass of islet tissue of the pancreas as a whole.
Islet cell transplantation evolved out of a desire to make use of viable islet tissue from otherwise nonviable whole glands.