A histochemical study of the odontoblast process

Abstract

Serial ground sections of sound, recently erupted premolars were stained with 0.0005 M methylene blue and 0.01–0.1% toluidine blue at pH 2.6–7.0, with Schiff reagent, the periodic acid-Schiff method, the combined alcian blue-PAS method of Mowry (1956) and the alloxan-Schiff method. Sections were also examined for alkaline phosphatase activity using Gomori's calcium-cobalt method and the azo dye technique. In the predentine and in the dentine up to a distance of about 120–200 μ from the predentine-dentine junction the contents of the dentinal tubule stained solidly and intensely with methylene blue and toluidine blue at pH 7.0, the PAS method used alone or in combination with alcian blue, and the alloxan-Schiff method. The limit of this staining corresponds with the level by which a well-formed translucent peritubular zone has appeared. The contents of the dentinal tubule also showed alkaline phosphatase activity up to this distance from the predentine-dentine junction. Beyond this level the contents of the dentinal tubule stained much less strongly with the methods used. At the junction between the peritubular matrix and the contents of the dentinal tubule, however, a deeply stained circle was found. It is impossible at present to decide whether this structure forms a part of the peritubular matrix or is the outer limit of the odontoblast process as it showed certain staining differences compared with either the peritubular matrix or the contents of dentinal tubule.