Intestinal M cells: The fallible sentinels?

Figure 1 Ultrastructure of the Peyer’s patches and FAE (Adapted by permission from Macmillan Publishers Ltd: Nature Reviews Immunology[32], copyright 2003). A: At low magnification, the dome shape of the Peyer’s patch protrudes between villi into the lumen of the intestine; B: At higher magnification, M cells can be seen as epithelial cells with surface microfolds rather than the microvilli that are seen on the surrounding conventional enterocytes; C: Antigen is taken up preferentially through M cells.