Presence of α‐naphthyl acetate esterase enzymes in dental and oral epithelium of guinea pig embryos

Abstract

This study examines the distribution of alpha-naphthyl acetate esterase enzymes in reduced enamel epithelium, i.e., post secretory ameloblasts (PSA) and external cells of reduced enamel epithelium (ERE) of continuously growing incisor and molar tooth germs and in the covering oral epithelium (OE). Jaws of guinea pig embryos, 25-50 days of gestation age, were pretreated, frozen, serially cut, and incubated with alpha-naphthyl acetate as substrate and hexazotized pararosaniline as capture agent for demonstration of enzyme activity. In addition, sections were preincubated with various inhibitors of enzyme activity. A strong enzyme reaction, essentially unaffected by pretreatment procedures, was demonstrated in all cells of PSA and ERE, and in suprabasal cells of OE. Preliminary characterization of the alpha-naphthyl acetate esterase enzymes by means of inhibitors suggests a prevailing presence of B-esterase enzymes in both oral and dental epithelia. PSA were selectively stained when 2 x 10(-3) M arsanilic acid was used as inhibitor, ERE were selectively inhibited by 10(-5) M eserine, and cells of OE were selectively stained when 2 x 10(-3) M HgCl2 was used as inhibitor. We therefore conclude that the alpha-naphthyl acetate esterase enzymes in combination with inhibitors may serve as histochemical markers for discrimination of dental and oral epithelium in the guinea pig prior to eruption of teeth.