Which part of the gastrointestinal tract is shown in the histological image below?
Cross section of ileum with a Peyer’s patch circled.
- A picture of Peyer’s Patches, which are organized lymphoid nodules commonly found in the small intestines. This histology section was taken from the ileum (NOT jejunum), the final section of the small intestines.
- Peyer’s patches (or aggregated lymphoid nodules) are organized lymphoid follicles, named after the 17th-century Swiss anatomist Johann Conrad Peyer.
- They are an important part of 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.
- Peyer’s patches are observable as elongated thickenings of the intestinal epithelium measuring a few centimeters in length.
- Peyer’s patches appear as oval or round lymphoid follicles (similar to lymph nodes) located in the mucosa layer of the ileum and extend into the submucosa layer.
- Peyer’s patches are characterized by the follicle-associated epithelium (FAE), which covers all lymphoid follicles.
- 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.