M cells (or microfold cells) are cells found in the follicle-associated epithelium of the Peyer's patch that have the unique ability to sample antigen from the lumen of the small intestine and deliver it via transcytosis to antigen presenting cells and lymphocytes located in a unique pocket-like structure on their basolateral side.
The filamentous brush border glycocalyx, an extracellular polysaccharide layer found throughout the intestine attached to enterocytes, is much thinner or absent on M cells.
Factors promoting the differentiation of M cells have yet to be elucidated, but they are thought to develop in response to signals from immune cells found in the developing Peyer's patch.
- Kraehenbuhl J, Neutra M. "Epithelial M cells: differentiation and function.". Annu Rev Cell Dev Biol. 16: 301–32. PMID 11031239. Link