part of part of M cell of gut epithelial cell of small intestine microfold cell of epithelium of small intestine A M cell that is part of the epithelium of small intestine. https://cellxgene.cziscience.com/cellguide/CL_1000353 Microfold cells, also widely known as M cells, are a distinct type of epithelial cell found in the gut, including the small intestine, specifically within the Peyer’s patches, a component of the gut-associated lymphoid tissue (GALT). M cells play a crucial role in the immune response within the intestine environment. These cells are characterized by microfolds (short microvilli, which give them their name), a reduced, thin glycocalyx, and a deeply invaginated basolateral membrane next to immune cells such as B cells, T cells, and macrophages, and DCs. These features allow the M cells to form the first point of contact between the gut lumen and the intestinal immune system. They are well-regulated gateways that capture and transport antigens, such as bacteria, viruses, and other foreign substances found in the lumen, to the underlying cells of the immune system. This specialized transport mechanism, called ‘transcytosis’, involves engulfment of these antigens from the apical side, transport across their cytoplasm, and release on the basolateral side of the cells, where immune responses can be initiated. Furthermore, M cells have complex interactions with members of the gut microbiota and other immune cells, making them essential for maintaining gut homeostasis. This cross-talk shapes the diversity and makeup of the gut microbiota, subsequently having a substantial impact on the host's health. In certain situations, pathogenic organisms can exploit the transcytosis mechanism to infiltrate the host's system, causing various infectious diseases. The overarching significance of M cells in the small intestine lies in their role of surveillance and protection against a wide range of potentially harmful pathogens, while also facilitating beneficial interactions with commensal microbes. (This extended description was generated by ChatGPT and reviewed by the CellGuide team, who added references, and by the CL editors, who approved it for inclusion in CL. It may contain information that applies only to some subtypes and species, and so should not be considered definitional.) FMA:263128 epithelium of small intestine small intestine