Answer: (<u>Note</u>: You will find the image with the highlighted structure in the attached file)
Peyer's patches (aggregated lymphoid nodules)
Explanation:
Peyer's patches are anatomical regions located under the mucosa of the gastrointestinal tract, specifically in the lamina propria of the thin intestine. These patches are nodules or cumulus of lymphatic tissue and other accessory cells, and this is why they represent a huge part of the mucosa´s immunity system.
Peyer's patches belong to the group of lymphoid tissue associated with the intestine, composed of lymphoid follicles distributed along the gastrointestinal tract.
A lymphoid follicle is a cumulus or aggregate of lymphoid cells that do not have a well-defined structure nor organization. In general, these follicles are isolated from each other in the intestine. But in the terminal ileum (The last portion of the thin intestine) they get so close that they might form a plaque. The Peyer´s patches are formed principally by lymphocytes B that synthesize immunoglobulin A, which has an important role in immunity.
