Ultrastructural investigation of M-cells and lymphoepithelial contacts in naso-pharyngeal associated lymphoid tissue (NALT).

The nasopharyngeal and palatine tonsil, two lymphoepithelial structures situated at the entrance of respiratory and gastrointestinal tracts, show striking similarity with lymphoid tissue of bronchus and gut (BALT, GALT). The information obtained by previous investigations in our laboratory on M-cells in the lymphoepithelium of the Peyer's patches (PP) served as a guidance in our search for M-cells in adenoids and tonsils.