M cells and host defense.
D000818:Animals; D004064:Digestive System / Q000166:cytology*; D004847:Epithelial Cells; D004926:Escherichia coli; D006801:Humans; D007107:Immune System; D008198:Lymph Nodes / Q000166:cytology*; D008285:Major Histocompatibility Complex; D009092:Mucous Membrane / Q000166:cytology; D012137:Respiratory System / Q000166:cytology*