Ultrastructural histochemistry of the dento‐epithelial junction

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Abstract
The dento‐epithelial junctions (DEJ) of Rhesus monkeys were studied by electron microscopy for their histochemical responses to colloidal thorium and ruthenium red. Both of these cationic dyues are useful markers for the detection of acidic carbohydrates. With colloidal thorium, deposits occurred on the intercellular cell surfaces but not on the surfaces facing the tooth. The basal lamina, dental cuticle, desmosomes and hemidesmosomes reacted negatively. With ruthenium red, cell surfaces, desmosomal junctions, the peripheral densities and the spaces between the peripheral densities and the cell membranes of hemidesmosomes stained intensely. The lamina densa was also stained, but the lamina lucida and dental cuticle were negatively reacting. The negative reactions of the basal lamina and dental cuticle after colloidal thorium demonstrate the lack of acidic carbohydrates in both layers. With ruthenium red and periodic acid‐oxidation, the dental cuticle was denoted again to be negative for acidic carbohydrates. As for the reaction positive basal lamina with ruthenium red, we interpreted that the reaction was not due to acidic carbohydrates but potentially attributed to a protien moiety.