Scanning and transmission electron microscopy on the epithelium of human palatine tonsils.

Twelve human palatine tonsils were studied by scanning and transmission electron microscopy. The epithelium lining the tonsillar crypts was shown to be stratified squamous in type, with an extensive system of channels occupying nearly the full thickness of the epithelium. The channels were infiltrated by lymphocytes, plasma cells and mononuclear phagocytic cells. Specialised surface cells, or M cells, were also seen. These had microvilli and surrounded lymphocytes which were brought very close to the crypt lumen. The presence of numerous holes in the crypt epithelium was thought to be an artefact resulting from the delicate nature of the M cells. These showed the organisation of the epithelium related to the function of the tonsil as part of the gut-associated lymphoid tissues. The tonsil has similarities to other gut-associated lymphoid organs but also has its own particular features.