Peyer's patch

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Peyer's patch
Cross section of ileum with a Peyer's patch circled.
Details
SystemLymphatic system
Identifiers
Latinnoduli lymphoidei aggregati
MeSHD010581
TA98A05.6.01.014
A05.7.02.009
TA22960, 2978
THH3.04.03.0.00020
FMA15054
Anatomical terminology

Peyer's patches (or aggregated lymphoid nodules) are organized

gut associated lymphoid tissue usually found in humans in the lowest portion of the small intestine, mainly in the distal jejunum and the ileum, but also could be detected in the duodenum.[2]

History

Peyer's patches had been observed and described by several anatomists during the 17th century,[3] but in 1677 Swiss anatomist Johann Conrad Peyer (1653–1712) described the patches so clearly that they were eventually named after him.[1][4] However, Peyer regarded them as glands which discharged, into the small intestine, some substance which facilitated digestion. It was not until 1850 that the Swiss physician Rudolph Oskar Ziegler (1828–1881) suggested, after careful microscopic examination, that Peyer's patches were actually lymph glands.[5]

Structure

Peyer's patches are observable as elongated thickenings of the

mucosa layer of the ileum and extend into the submucosa
layer. The number of Peyer's patches peaks at age 15–25 and then declines during adulthood.[2] In the distal ileum, they are numerous and they form a lymphoid ring. At least 46% of Peyer's patches are concentrated in the distal 25 cm of ileum in humans. It is important to note that there are large variations in size, shape, and distribution of Peyer's patches from one individual to another one.[6] In adults, B lymphocytes are seen to dominate the follicles' germinal centers.
T lymphocytes are found in the zones between follicles. Among the mononuclear cells, CD4+/CD25+ (10%) cells and CD8+/CD25+ (5%) cells are more abundant in Peyer's patches than in the peripheral blood.[7]

Peyer's patches are characterized by the follicle-associated epithelium (FAE), which covers all lymphoid follicles.

microfold cells, which provide uptake and transport of antigens from lumen.[8] Moreover, basal lamina of follicle-associated epithelium is more porous compared to intestinal villus.[11] Finally, follicle-associated epithelium is less permeable for ions and macromolecules, basically due to higher expression of tight junction proteins.[12]

Function

Because the

mucosa
.

Pathogenic microorganisms and other

CD122-targeted interleukin-2(IL-2) signaling. Additionally, the B cell population can be restored. [13]

Peyer's patches are covered by a special follicle-associated epithelium that contains specialized cells called microfold cells (

mesenteric lymph nodes where the immune response is amplified. Activated lymphocytes pass into the blood stream via the thoracic duct
and travel to the gut where they carry out their final effector functions. The maturation of B-lymphocytes takes place in the Peyer's patch.

Clinical significance

Although important in the immune response, excessive growth of lymphoid tissue in Peyer's patches is pathologic, as

hypertrophy of Peyer's patches has been closely associated with idiopathic intussusception
.

Having too many or larger than normal Peyer's patches is associated with an increased risk of

prion diseases, and intussusception in children. A history of viral illness is a risk factor for enlarged or inflamed Peyer's patches.[17]

Salmonella typhi and poliovirus also target this section of the intestine.[18]

See also

References

  1. ^ a b Peyer, Johann Conrad (1677). Exercitatio Anatomico-Medica de Glandulis Intestinorum, Earumque Usu et Affectionibus [Anatomical-medical essay on the intestinal glands, and their function and diseases] (in Latin). Schaffhausen, Switzerland: Onophrius à Waldkirch.
    • Reprinted as: Peyer, Johann Conrad (1681). Exercitatio Anatomico-Medica de Glandulis Intestinorum, Earumque Usu et Affectionibus (in Latin). Amsterdam, Netherlands: Henrik Wetstein.
    • Peyer referred to Peyer's patches as plexus or agmina glandularum (clusters of glands). From (Peyer, 1681), p. 7: "Tenui a perfectiorum animalium Intestina accuratius perlustranti, crebra hinc inde, variis intervallis, corpusculorum glandulosorum Agmina sive Plexus se produnt, diversae Magnitudinis atque Figurae." (I knew from careful study of more advanced animals, the intestines bear — often here and there, at various intervals — clusters of glandular small bodies or "plexuses" of diverse size and shape.) From p. 15: "(has Plexus seu agmina Glandularum voco)" (I call them "plexuses" or clusters of glands) He described their appearance. From p. 8: "Horum vero Plexuum facies modo in orbem concinnata; modo in Ovi aut Olivae oblongam, aliamve angulosam ac magis anomalam disposita figuram cernitur." (But the configurations of these "plexuses" are arranged at one time in a circle; at another time, it is seen in an egg [shape] or an oblong olive [shape] or other faceted and more irregularly arranged shape.) Drawings of Peyer's patches appear after pages 22 and 24.
  2. ^
    PMID 18668776
    .
  3. ^ Haller, Albrecht von (1765). Elementa Physiologiae corporis humani [Elements of the physiology of the human body] (in Latin). Vol. 7. Bern, Switzerland: Societas Typographica. p. 35. Anatomists who mentioned Peyer's patches included:
  4. ^ There were many earlier names for Peyer's patches:
  5. ^ Ziegler, Rudolph Oskar (1850) Ueber die solitären und Peyerschen Follikel : Inaugural-Abhandlung, der medicinischen Facultät der Julius-Maximilians-Universität zu Würzburg vorgelegt [On solitary and Peyer's follicles: Inaugural treatise, submitted to the medical faculty of the Julius-Maximilians-University of Würzburg] (in German) Würzburg, (Germany): Friederich Ernst Thein. From p. 37: "Ebensogross, wo nicht grösser ist die Aehnlichkeit der sogenannten Peyer'schen Drüsen und der Lymphdrüsen." (Just as great, if not greater, is the resemblance between the so-called Peyer's glands and the lymph glands.) From p. 38: " … ja, man könnte selbst versucht sein, die letzteren für nichts als eine Art von zwischen den Wänden der Darmsschleimhaut eingebetteten Lymphdrüsen zu halten." ( … indeed, one could even be tempted to regard the latter [i.e., the Peyer's patches] as nothing but some type of lymph glands [which are] embedded between the walls of the intestinal mucosa.)
  6. S2CID 22514793
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  18. ^ Pascall, C R; Stearn, E J; Mosley, J G (1980-07-05), "Short Reports",
    PMID 7407483
    , Unlike S hadar peritonitis, S typhi peritonitis is due to perforation of Peyer's patches.

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