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islets of Langerhans

  (ī'lĭts; läng'ər-häns') pronunciation
pl.n.

Irregular clusters of endocrine cells scattered throughout the tissue of the pancreas that secrete insulin and glucagon. Also called islands of Langerhans.

[After Paul Langerhans (1847–1888), German pathologist.]


 
 
Food and Nutrition: islets of Langerhans

The endocrine parts of the pancreas; glucagon is secreted by the α-cells and insulin by the β-cells.

 
Britannica Concise Encyclopedia: islets of Langerhans

Irregularly shaped patches of endocrine tissue in the pancreas. The normal human pancreas has about one million of them. Beta cells, the most common islet cells, produce insulin to regulate blood glucose. (Inadequate production of insulin is characteristic of diabetes mellitus.) Alpha cells produce an opposing hormone, glucagon, which releases glucose from the liver and fatty acids from fat tissue; these favour insulin release and inhibit glucagon secretion. Delta cells produce somatostatin, which inhibits somatotropin (a major pituitary hormone), insulin, and glucagon; its metabolic role is not clear. Small numbers of another type of cell secrete pancreatic polypeptide, which slows down nutrient absorption. See also endocrine system.

For more information on islets of Langerhans, visit Britannica.com.

 
Sports Science and Medicine: islets of Langerhans

Endocrine tissue in the pancreas which secretes insulin and glucagon.

 
Wikipedia: islets of Langerhans
A porcine islet of Langerhans.  The left image is a brightfield image created using hematoxylin stain; nuclei are dark circles and the acinar pancreatic tissue is darker than the islet tissue.  The right image is the same section stained by immunofluorescence against insulin, indicating beta cells.
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A porcine islet of Langerhans. The left image is a brightfield image created using hematoxylin stain; nuclei are dark circles and the acinar pancreatic tissue is darker than the islet tissue. The right image is the same section stained by immunofluorescence against insulin, indicating beta cells.
Islets of Langerhans, haemalum-eosin stain.
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Islets of Langerhans, haemalum-eosin stain.
Section of pancreas of dog. X 250.
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Section of pancreas of dog. X 250.

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.

Cell types

Hormones produced in the Islets of Langerhans are secreted directly into the blood flow by (at least) four different types of cells:

Islets can influence each other through paracrine and autocrine communication, and beta-cells are coupled electrically to beta-cells (but not to other cell-types).

Paracrine feedback

The paracrine feedback system of the islets of Langerhans has the following structure:

  • Insulin: Activates beta cells and inhibits alpha cells.
  • Glucagon: Activates alpha which activates beta cells and delta cells.
  • Somatostatin: Inhibits alpha cells and beta cells.

Electrical activity

Electrical activity of pancreatic islets has been studied using patch clamp techniques, and it has turned out that the behavior of cells in intact islets differs significantly from the behaviour of dispersed cells. and is about 30 cm in width

As a treatment for type I diabetes

Since the beta cells in islets of Langerhans are destroyed in type I diabetes, clinicians and researchers are actively pursuing islet transplantation technology as a means of curing this disease.

Transplantation

With the possiblity of restoring beta cells, the Chicago Project headed at University of Illinois at Chicago Medical Center is probing for a way to regenerate beta cells in the islets and have them cultivate on their own within a human pancreas. With that being said, beta cells experience apoptosis early and thus become destroyed within a normal-functioning pancreas. The source of this seems to come from the transfer of Pander, a gene that enters in by attaching to RNA. This process of RNA transportation can be found in the glucose that bombards the beta cells. The genetic encoding found within Pander causes the beta cells to stop during the S phase of mitosis and head straight to apotasis. This ceases much of the reproduction of beta cells within the Islets.

References in pop culture

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Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.  Read more
Britannica Concise Encyclopedia. Britannica Concise Encyclopedia. © 2006 Encyclopædia Britannica, Inc. All rights reserved.  Read more
Sports Science and Medicine. The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Islets of Langerhans" Read more

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