Visualization of proteoglycans and membrane-associated components in rat incisor predentine and dentine using ruthenium hexammine trichloride.

Ruthenium hexammine trichloride (RHT) used as a probe to visualize anion groups in the predentine and dentine of rat incisors, showed a complex distribution pattern including: intercellular proteoglycans (Pg), detected in the predentine as granules 10-15 nm in diameter and as filaments. Non-aggregating Pg was observed in the spaces between collagen fibres as an amorphous group substance. The dentine included smaller RHT-positive granules, observed after thin-section demineralization; pericellular aggregates, 30-50 nm in diameter, which were absent at the onset of the cell coat along the plasma-membrane of the odontoblast process and of the membrane itself. All these RHT-positive components might be Pg and/or sialoglyconjugates and glyco- or phospholipids present on the plasma membrane.