Peyer
Peyer is a surname of Swiss origin and, in scientific contexts, most commonly refers to Peyer's patches, a key component of the gut immune system. Peyer's patches are aggregated lymphoid nodules in the ileum and form part of the gut-associated lymphoid tissue (GALT). They are distributed along the distal small intestine and consist of lymphoid follicles with germinal centers; the overlying epithelium contains M cells that sample luminal antigens and transport them to underlying immune cells. B cells within Peyer's patches can differentiate into IgA-secreting plasma cells, contributing to mucosal immunity. T cells, dendritic cells, and macrophages participate in antigen presentation and in initiating adaptive immune responses. Peyer's patches play roles in immune surveillance of intestinal contents, tolerance to harmless antigens, and defense against pathogens. They can enlarge during infection or inflammation and are sometimes involved in the pathogenesis or modulation of inflammatory bowel diseases such as Crohn's disease.
The patches are named after Johann Conrad Peyer, a Swiss anatomist who described the structures in the