Formation of the tonsillar corpuscle.

In this study of the human palatine tonsil we examined epithelial structures found always in the vicinity of the crypts and closely resembling thymic Hassall's corpuscles. We propose that in the reactive tonsillar lymphoid tissue these corpuscles form as a result of occlusion of fine microcrypts by the expanding lymphoid follicles during antigenic stimulation. The reticulated epithelial cells lining these microcrypts may then loose their polarisation, and gradually degenerate deep in the parenchyma, forming concentrically arranged parakeratotic pearls, rather than desquamate at the free epithelial surface. The structural similarities of the tonsillar and Hassall's corpuscles may be explained by endodermal embryological origin of the primordia of both organs, and by the specific degenerative properties of epithelia in the lymphoepithelial immune organs.