Immunohistochemical markers of tonsillar crypt epithelium

The crypt epithelium of human palatinal tonsils is a specialized squamous epithelium characterized by the presence of intraepithelial passages which are filled by non-epithelial cells. The passages are covered by the so-called M cells. This reticulated epithelium (reticulum = network) is a highly differentiated one. In the present study immunohistochemical markers were searched for the discrimination between the superficial mucosal squamous epithelium (from which the crypts were developed) and the reticulated crypt epithelium. The reticulated epithelium is replaced by simple squamous epithelium in the course of recurrent tonsillitis. The immunohistochemical characteristics of this metaplastic epithelium were also studied. The superficial epithelium expressed blood group antigens extensively, but these antigens were almost absent from the crypt epithelium. Epithelial membrane antigen was present only in the superficial layers of the surface epithelium. Abundant positivity was characteristic for the reticulated epithelium. The metaplastic foci in the crypts were identical with the surface squamous epithelium using these markers.