Mucopolysaccharide localization in gingival epithelium I. An autoradiographic demonstration.

Short incubations, at 37°C, of small freshly excised pieces of healthy human gingivae incorporated [³⁵S]-sulphate and [³H]-acetate into macromolecular material which could be precipitated intercellularly in the epithelium. Following radioactively pulse-chased incubations, such localization was observed by autoradiography on cryostat histological sections fixed in cetylpyridinium chloride. Critical electrolyte salt concentration elution indicated that most of the intercellular material was soluble in 0.63M-MgCl₂, and any material which remained was intracellular. In vitro and in vivo incorporation studies were compared. These data corroborate biochemical studies (Wiebkin, Bartold & Thonard 1979) together with other histochemical observations that proteoglycans (mucopolysaccharides) are a major intercellular component of human gingival epithelium. Molecular conformation and the relatively rapid synthesis and secretion rate for this class of epithelial macromolecule may explain the lack of susceptibility of this material in the intercellular site, both to degradation by some specific enzymes previously reported and to elution with critical salt concentrations from cationic detergent precipitates. The method described, together with in vivo incorporation studies, provides a useful technique for studying direct effects of some microenvironmental influences on gingival epithelium. [ABSTRACT FROM AUTHOR]