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Other Terms: Faucial tonsil, Tonsilla palatina, Tonsille palatine
Palatine tonsils, commonly called “the tonsils,” are masses at the entrance to the upper respiratory and gastrointestinal tracts. They can be seen at the back of the throat on the right and left sides. They contain four lymphoid compartments: the reticular crypt epithelium, the extrafollicular area, the mantle zones of lymphoid follicles, and the follicular germinal centers. All four compartments influence immune functions, and the tonsillar epithelium is the first part exposed to the outside environment. The tonsils are covered by stratified squamous epithelium, and due to their vast system of both deep and partly branched crypts, have a large internal surface that allows contact between the lymphoid tissue and environmental influences. There are about 10 to 30 crypts in an average tonsil, and their estimated epithelial surface area is 295 cm2, besides the 45 cm2 of epithelium covering the oropharyngeal surface. One of the main immunocompetent tissues of the oropharynx, it is a site of and probable focus for infections. As a significant immune initiatory tissue, the purpose is to prevent exogenous material from entering the body through mucosal sites. The tonsillar crypts provide early exposure of infectious organisms that may be introduced to the body to the cells of the immune system. However, they often provide an environment that is very inviting to bacteria, so solid stones may be formed by bacterial colonies in the crypts.