islets of Langerhans

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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.


References in periodicals archive ?
Thousands of islet cells were painstakingly separated to ensure that only the highest quality, individual cells were analysed.
The challenge with the device is the number of islet cells it can accommodate successfully--only about 1,000.
The results of the study shows that the majority of functional islet cell tumors are usually less than 3 cm in size at the time of diagnosis, and are typically homogenous hyperenhancing lesions and best seen during arterial phase.
Phase III, randomized, double-blind trial of sunitinib versus placebo in patients with progressive, well-differentiated pancreatic islet cell tumours.
Of the 51 patients who did receive 2,000 or more islet cells, 37 required only intermittent insulin or none at all during long-term follow-up.
This decision is complicated by the time-dependent decrease in cadaveric islet cell function, said James Markmann, M.
We have shown that cell transplantation, with both pancreatic islet cells and previously with hepatocyte (liver) cells, can offer patients a valuable alternative to conventional treatments.
Caught up in the frenzy over the supposed unlimited curative powers of embryonic stem cells, many have begun to argue that harvesting islet cells from cadavers is inefficient and unnecessary.
Laboratory tests reveal that human islet cells treated with GLP-1 maintained their shape and structural integrity for a longer period of time than untreated samples.
The company believes that its islet cell transplantation technology has the potential to dramatically improve the quality of life for people with insulin-dependent diabetes.
The following journal articles illustrate the current worldwide experience with islet cell transplantation and the clinical outcomes achieved as well as the problems encountered with this treatment.