An Electron Microscopic Study on the Epithelium of the Rat Tongue.

There are available results of electron microscopic studies as. regards the oral mucosa by such researchers as Sognnaes and Albright (1956, 1958), Themann (1958), Fasske and Themann (1959), Frenkel (1959), Albright (1960), Rhodin and R eith (1962) and Arai (1961, 1962). But all of them fail to give a description of the epithelium of the tongue, and only Rhodin and R e i t h give a brief mention of the tongue epithelium in their study on keratinization. The epithelium of the tongue is a stratified squamous epithelium by reason of being covered by the oral mucosa but we find keratinization on its dorsal portion and this epithelium has a special structure in that it forms numerous papillae. As a result of detailed study by Rhodin and R e i t h, the mechanism of the formation of keratin is regarded as being due to RNP particles (ribonucleoprotein particles) which surround keratohyalin granules. Kubota et al. explained, on the basis of their optic microscopic data, that the genesis of keratohyalin granules which are closely bound up with keratinization might derive from the nucleolus. Although a. recent study by Brody (1959) referred to the relationship between keratinization and keratohyalin granules, he omitted reference to their origin. In the present study, the authors have conducted an electron microscopic investigation into the lingual epithelium of rats and obtained the findings that indicate mitochondriae to be intimately related to the formation of these keratohyalin granules. Together