What are Peyer's patches?

• A. Villi
• B. Microvilli
• C. Peyer's patches
• D. Goblet cells

Answer: (C)

Peyer's patches are organized lymphoid tissue in the lining of the small intestine, mainly in the distal ileum, and they are part of the gut-associated lymphoid tissue (GALT). Their main job is immune surveillance: they monitor what passes through the gut lumen and help initiate immune responses to pathogens and dietary antigens. Structurally, they are clusters of lymphoid follicles within the mucosa and submucosa, containing B cells, T cells, and other immune cells. A key feature is the presence of specialized M cells that sample antigens from the intestinal lumen and deliver them to underlying immune cells, supporting the production of mucosal IgA.

This helps explain why Peyer's patches aren’t the same as absorptive surface features like villi or microvilli, which are finger-like projections that increase surface area for absorption, or as mucus-secreting goblet cells.