Islets of Langerhans


Islets of Langerhans

Islets of Langerhans is the area in which the endocrine (i.e., hormone-producing) cells of the pancreas are grouped. Discovered in 1869 by the famous 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; their combined mass 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) five different types of cells:cite journal |author=Elayat AA, el-Naggar MM, Tahir M |title=An immunocytochemical and morphometric study of the rat pancreatic islets |journal=J. Anat. |volume=186 ( Pt 3) |issue= |pages=629–37 |year=1995 |pmid=7559135 |doi=]
* Alpha cells producing glucagon (15-20% of total islet cells)
* Beta cells producing insulin and amylin (65-80%)
* Delta cells producing somatostatin (3-10%)
* PP cells producing pancreatic polypeptide (3-5%)
* Epsilon cells producing ghrelin. (<1%)

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:cite book |author=Wang, Michael B.; Bullock, John; Boyle, Joseph R. |title=Physiology |publisher=Lippincott Williams & Wilkins |location=Hagerstown, MD |year=2001 |pages= |isbn=0-683-30603-0 |oclc= |doi=]
* 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 behavior of dispersed cellscite journal |author=Pérez-Armendariz M, Roy C, Spray DC, Bennett MV |title=Biophysical properties of gap junctions between freshly dispersed pairs of mouse pancreatic beta cells |journal=Biophys. J. |volume=59 |issue=1 |pages=76–92 |year=1991 |pmid=2015391 |doi=] .

As a treatment for type I diabetes

Because the beta cells in the islets of Langerhans are destroyed in type I diabetes, clinicians and researchers are actively pursuing islet transplantation technology as a means of curing this diseasecite journal |author=Meloche RM |title=Transplantation for the treatment of type 1 diabetes |journal=World J. Gastroenterol. |volume=13 |issue=47 |pages=6347–55 |year=2007 |pmid=18081223 |doi=10.3748/wjg.13.6347] . Rachel Harris, islet cell recipient, was transplanted at the Diabetes Research Institute in Miami, Florida. In June of 2004, Rachel became the world's longest surviving insulin-free diabetic according to the Miami Herald (published Feb. 13, 2004). [www.islets.fanspace.com]

Islet transplantation currently requires potent immunosuppression to prevent host rejection of donor islets. An alternative source of beta cells, such an islets derived from adult stem cells or progenitor cells of a diabetic would eliminate the need for immuosuppressive therapy, and be safer for diabetics.cite journal |author=Chatenoud L |title=Chemical immunosuppression in islet transplantation--friend or foe? |journal=N. Engl. J. Med. |volume=358 |issue=11 |pages=1192–3 |year=2008 |pmid=18337609 |doi=10.1056/NEJMcibr0708067] .

Transplantation

With the possibility of restoring beta cells, the Chicago Project headed at University of Illinois at Chicago Medical Center is investigating ways to regenerate beta cells "in vivo". With that being said, beta cells experience apoptosis early and thus are destroyed within a normal-functioning pancreas. The source of this seems to come from the transfer of Pander, a gene that works by attaching to RNAcite journal |author=Cao X, Gao Z, Robert CE, "et al" |title=Pancreatic-derived factor (FAM3B), a novel islet cytokine, induces apoptosis of insulin-secreting beta-cells |journal=Diabetes |volume=52 |issue=9 |pages=2296–303 |year=2003 |pmid=12941769|doi=10.2337/diabetes.52.9.2296] . Pander, when active, causes the beta cells to be blocked at S phase, which induces apoptosis. This loss of beta cell mass eventually leads to a loss of most of the transplanted beta cells.

References in pop culture

* A Harlan Ellison short story titled "Adrift Just Off the Islets of Langerhans: Latitude 38° 54' N, Longitude 77° 00' 13" W" appears in his collection Deathbird Stories. (Those coordinates locate the intersection of H and 2nd N.E. in Washington, D.C., behind Union Station)
* American parodist "Weird Al" Yankovic released a song entitled Pancreas on his album "Straight Outta Lynwood", which continually repeats the lyrics "Insulin, glucagon, comin' from the Islets of Langerhans" during the final minute of the song.
*On their comedy album "How Can You Be in Two Places at Once When You're Not Anywhere at All", The Firesign Theatre referred to immigrants who came "from little towns with strange names like Smegma, Spasmodic, Frog, and the far-flung Isles of Langerhans".
*In the "Lord of the Rings" parody book Bored of the Rings by the Harvard Lampoon, the map features two islands situated close to each other labelled "The Isles of Langerhans".
*Col. Bruce Hampton & The Late Bronze Age released their 1982 LP "Isles of Langerhan" featuring the opening cut of the same name.

Gallery

Hormones/Islet Architecture

References

External links

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Look at other dictionaries:

  • islets of Langerhans — or islands of Langerhans [läŋ′ər hänz΄] n. 〚after P. Langerhans (1847 88), Ger histologist〛 irregular groups of endocrine cells in the pancreas that produce the hormone insulin: their degeneration may cause diabetes mellitus * * * …   Universalium

  • islets of Langerhans — or islands of Langerhans [läŋ′ər hänz΄] n. [after P. Langerhans (1847 88), Ger histologist] irregular groups of endocrine cells in the pancreas that produce the hormone insulin: their degeneration may cause diabetes mellitus …   English World dictionary

  • islets of Langerhans — ► PLURAL NOUN ▪ groups of cells in the pancreas that secrete the hormones insulin and glucagon. ORIGIN named after the German anatomist Paul Langerhans (1847 88) …   English terms dictionary

  • Islets of Langerhans — Known as the insulin producing tissue, the islets of Langerhans do more than that. They are groups of specialized cells in the pancreas that make and secrete hormones. Named after the German pathologist Paul Langerhans (1847 1888), who discovered …   Medical dictionary

  • islets of Langerhans — /ˌaɪləts əv ˈlæŋəhæns/ (say .uyluhts uhv languhhans) plural noun See pancreas. Also, islands of Langerhans. {named after Paul Langerhans, 1847–88, German physician} …   Australian English dictionary

  • islets of Langerhans — noun cell clusters in the pancreas that form the endocrine part of that organ; secrete insulin and other hormones • Syn: ↑islands of Langerhans, ↑isles of Langerhans • Hypernyms: ↑endocrine gland, ↑endocrine, ↑ductless gland • …   Useful english dictionary

  • islets of Langerhans — small groups of endocrine cells scattered through the material of the pancreas. There are three main histological types: alpha (a) cells, which secrete glucagon; beta (b) cells, which produce insulin; and delta (d) cells, which release… …   Medical dictionary

  • islets of Langerhans — [ laŋəhanz] plural noun groups of pancreatic cells secreting insulin and glucagon. Origin C19: named after the German anatomist Paul Langerhans …   English new terms dictionary

  • islets of Langerhans — small groups of endocrine cells scattered through the material of the pancreas. There are three main histological types: alpha (α) cells, which secrete glucagon; beta (β) cells, which produce insulin; and D cells, which release somatostatin and… …   The new mediacal dictionary

  • Islets of Langerhans — Groups of cells found within the pancreas: A cells and B cells secrete insulin and glucagon. See also D cells …   Dictionary of molecular biology


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