Tonsils and lympho-epithelial structures in the pharynx as immuno-barriers.

The tonsils are mucosa-associated lymphoid organs. Several details regarding their normal function and pathological alteration are still unknown. In this review the relationship of the tonsils to similar lymphoid organs is discussed, the possibilities of antigen uptake (M cells and micropores of the crypt epithelium) are demonstrated, and alterations of the crypt epithelium due to recurrent tonsillitis are described. Further studies are required for the better understanding of tonsillar diseases.