The sequence of reticularisation of epithelium of human palatine tonsil: scanning electron microscopic study.

The changes appearing during the development of the human palatine tonsil, both in the surface and in the tonsillar crypt epithelium, were studied from samples of the 16th to 40th prenatal weeks. From the 18th week, we observed areas of mesh-like epithelium in an originally homogeneous stratified squamous epithelium, i.e. the reticularisation began in the tonsillar crypt epithelium. The important role of the epithelial basal membrane in this process is discussed. The diffuse spongy-form type of reticularisation as well as the formation of the intraepithelial passages between the epithelial columns are described. The lymphoid cells and macrophages migrated through these microcrypts and they were frequently seen near the crypt epithelial micropores on the surface of the reticularised epithelium.