The histochemical localization of calcium in the keratohyalin granules of human oral epithelium

Abstract

KERATOHYALIN granules were first observed and recorded in skin by ALJFMAMMER (1869). RANVIER (1879) was of the opinion that they consisted of a lipid material, “eleidin”. It was WALDEYER (1882) who first named these granules “keratohyalin granules”, as he assumed they must have some relationship to keratinization. The granular layer owes its appearance to the keratohyalin granules. In the oral cavity of man a granular layer is found wherever keratinization occurs, but it may not always be well-developed. The buccal mucosa, floor of the mouth, ventral aspect of the tongue and soft palate do not normally keratinize, and in these sites a granular layer is absent. If pathological keratinization occurs in these sites a granular layer forms. The gingiva, hard palate and tips of the papillae on the dorsum of the tongue are normally keratinized in the human oral cavity. The formation, function and fate of keratohyalin granules is not well understood and little is known of their chemical nature. LEUCHTENBERGER and LUND (1951) have stated that the keratohyalin granules of skin contain RNA but JARRJTIT, SPEARMAN and HARDY (1959) have found no evidence that either RNA or DNA is present. Keratohyalin granules of skin are usually aggregated at the poles of the nucleus and may be stained with most basic dyes as well as with acid dyes such as Congo red and acid fuchsin. The deep staining of the granules has been thought to be due to the presence of metallic ions which act as mordants (SMITH and PARKHURST, 1949). OPDYKE (1952) has micro-incinerated sections of skin and found that keratohyalin granules are the most heavily mineralized cytoplasmic components of the cells of the granular layer and is of the opinion that they contain calcium. JARRETT and SPEARMAN (1964) have also found calcium in keratohyalin granules. Although the role of calcium is not well understood, they believe that it acts as an activator of certain enzymes, such as adenosine triphosphatase, besides being essential for the normal functioning of the epidermis. It is known that patients with low blood calcium levels tend to develop disorders of the epidermal cells associated with abnormal keratin production, and that the clinical state of the skin improves following correction of the blood levels (GARRFXTS and DENT, 1960). The present investigation was carried out because of the lack of information concerning the presence of calcium in the keratohyalin granules of human oral mucosa.