(histology) Aggregates of lymph nodules beneath the epithelium of the ileum.
| Sci-Tech Dictionary: Peyer's patches |
(histology) Aggregates of lymph nodules beneath the epithelium of the ileum.
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| Medical Dictionary: aggregated lymphatic follicles |
Collections of many lymphoid follicles closely packed together, forming oblong elevations on the mucous membrane of the small intestine. Also called aggregate glands, agminate glands, Peyer's patches.
| Veterinary Dictionary: Peyer's patches |
Oval, elevated patches of closely packed lymph follicles in mucous and submucous layers of the small intestine. Called also aggregated lymphatic nodules.
| Wikipedia: Peyer's patch |
Peyer's patches are organized lymphoid tissue, named after the 17th-century Swiss anatomist Johann Conrad Peyer. They are aggregations of lymphoid tissue that are usually found in the lowest portion of the small intestine ileum in humans; as such, they differentiate the ileum from the duodenum and jejunum.
Peyer's patches are observable as elongated thickenings of the intestinal epithelium measuring a few centimeters in length. About 30 are found in humans. Microscopically, Peyer’s patches appear as oval or round lymphoid follicles (similar to lymph nodes) located in the lamina propria layer of the mucosa and extending into the submucosa of the ileum. The mucosal surface is exposed to invasive microorganisms released from the blood, so Immunoglobulin A (IgA) is the first line of defense.
In adults, B lymphocytes are seen to predominate in the follicles' germinal centers. T lymphocytes are found in the zones between follicles.
Because the lumen of the gastrointestinal tract is exposed to the external environment, much of it is populated with potentially pathogenic microorganisms. Peyer's patches thus establish their importance in the immune surveillance of the intestinal lumen and in facilitating the generation of the immune response within the mucosa.
Pathogenic microorganisms and other
Peyer's patches are covered by a special epithelium that contains specialized cells called microfold cells M cells which sample antigen directly from the lumen and deliver it to antigen-presenting cells (located in a unique pocket-like structure on their basolateral side). B-cells and memory cells are stimulated upon encountering
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.
The hypertrophy of Peyer's patches has also been associated with susceptibility to transmissible spongiform encephalopathies (commonly known as prion diseases).
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| The Immune System | |
| M cell | |
| Johne's disease |
| Locatoin of Peyer's patches? | |
| Where is the peyer's patches found? | |
| In which portion of the small intestine are the Peyer's patches located? |
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