Islets of Langerhans
199453
223796402
2008-07-05T21:16:55Z
Mr.roco.wilson
7427032
[[Image:Mouse islet LM SolimenaLab.jpg|thumbnail|300px|This photograph shows a [[mouse]] pancreatic islet, an often spherical group of [[hormone]]-producing [[biological cell|cells]]. [[Insulin]] is labelled here in green, [[glucagon]] in red, and the [[cell nucleus|nuclei]] in blue.]]
[[Image:Suckale08 fig2 islet structure.jpg|thumbnail|300px|The diagram shows the structural differences between [[rat]] islets (top) and [[humans]] islets (bottom) as well as the [[ventral]] part (left) and the [[dorsal]] part (right) of the [[pancreas]]. Different cell types are colour coded. Rodent islets, unlike the human ones, show the characteristic [[insulin]] core.]]
[[Image:Islet.png|right|thumbnail|300px|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 cell]]s.]]
[[Image:Langerhanssche Insel.jpg|thumb|300px|Islets of Langerhans, hemalum-eosin stain.]]
[[Image:Gray1105.png|thumbnail|300px|Illustration of dog pancreas. 250x.]]
The [[endocrine]] (i.e., [[hormone]]-producing) cells of the [[pancreas]] are grouped in the '''islets of Langerhans'''. 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 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) five different types of cells:<ref name="pmid7559135">{{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=}}</ref>
* [[Alpha cell]]s producing [[glucagon]] (15-20% of total islet cells)
* [[Beta cell]]s producing [[insulin]] and [[amylin]] (65-80%)
* [[Delta cell]]s producing [[somatostatin]] (3-10%)
* [[PP cell]]s producing [[pancreatic polypeptide]] (3-5%)
* [[Epsilon cell]]s 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:<ref name="isbn0-683-30603-0">{{cite book |author=Wang, Michael B.; Bullock, John; Boyle, Joseph R. |title=Physiology |publisher=Lippincott Williams & Wilkins |location=Hagerstwon, MD |year=2001 |pages= |isbn=0-683-30603-0 |oclc= |doi=}}</ref>
* 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 cells<ref name="pmid2015391">{{cite 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=}}</ref>.
==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 disease<ref name="pmid18081223">{{cite 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}}</ref>. 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).<ref>www.islets.fanspace.com</ref>
Islet transplantation currently requires potent [[immunosuppression]] to prevent host [[rejection]] of donor islets. An alternative source of [[beta cell]]s, such an islets derived from [[adult stem cells]] or [[progenitor cell]]s of a diabetic would eliminate the need for immuosuppressive therapy, and be safer for diabetics.<ref name="pmid18337609">{{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}}</ref>.
==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 [[RNA]]<ref name="pmid12941769">{{cite 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}}</ref>. 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 (Washington, D.C.)|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 [[islets of Langerhans|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 labled "The Isles of Langerhans".
==External links==
* {{MeshNumber|A03.734.414|Islets+of+Langerhans}}
* {{OklahomaHistology|80_14}} - "Pancreas"
* Diabetes Research Institute [http://www.drinet.org]
* Islet Cell Transplant Recipients [http://www.islets.fanspace.com]
==Gallery==
'''Hormones/Islet Architecture'''
<gallery>
Image:PancreaticPolypeptide.jpg|''Mouse islet immunostained for pancreatic polypeptide''.
Image:InsulinIHC.jpg|''Mouse islet immunostained for insulin''.
Image:Glucagon.jpg|''Mouse islet immunostained for glucagon''.
</gallery>
{{endocrine_pancreas}}
{{Digestive glands}}
{{Endocrine system}}
==References==
{{reflist}}
[[Category:Endocrine pancreas]]
[[ar:جزر لانغرهانس]]
[[cs:Langerhansovy ostrůvky]]
[[de:Langerhans-Inseln]]
[[es:Islotes de Langerhans]]
[[eo:Insuletoj de Langerhans]]
[[fa:جزایر لانگرهانس]]
[[fr:Îlots de Langerhans]]
[[it:Isole di Langerhans]]
[[he:איי לנגרהנס]]
[[pam:Islets of Langerhans]]
[[la:Insulae pancreaticae]]
[[nl:Eilandjes van Langerhans]]
[[ja:ランゲルハンス島]]
[[no:Langerhanske øyer]]
[[nn:Dei langerhanske øyane]]
[[pl:Wysepki Langerhansa]]
[[pt:Ilhotas de Langerhans]]
[[sv:Langerhanska öarna]]
[[zh:胰岛]]