The Histochemical Localization of Alkaline Phosphatase in Tooth Supporting Tissues of Rat

Abstract

1. The distributions of alkaline phosphatase in the tooth supporting tissues (paradentium), using the decalcifying sections of the upper and lower molars of the rats ranging from the first day after birth to the stage of maturity, have been investigated histochemically through GOMORI's method.2. Alkaline phosphatase is distributed through the whole periodontal membrane (Fig. 1, 6 and 7). The enzymatic reactions of the fibroblasts situated in SHARPEY's fibers are intensive in grade in the periodontal membrane, but the reactions of SHARPEY's fibers are themselves lower than those of the fibroblasts (Fig. 2). The enzymatic activities in each element consisting of the periodontal membrane are more intensive in the region adjacent to the alveolar bone, than in all the other regions (Figs. 1, 6, 7, 9, 10 and 11). And, in the regions where new bony matrix is formed actively, in which newly elaborated SHARPEY's fibers are inserted, both SHARPEY's fibers and the fibroblasts, particulary, show intensive reactions on one hand (Fig. 2, 8, 9 and 10). But, on the other hand, the reactions of the periodontal membrane adjcent to the cementum, under normal conditions, are not so intensive. The same is found in both the surface of the cellular cementum (Figs. 1 and 11) and the acellular (fibrous) cementum (Fig. 2), and, further, in the surface of the forming cementum.The intensity of enzymatic reactions of SHARPEY's fibers and the fibroblasts are different in several portions of periodontal membrane: the fibers of horizontal, transseptal and interradicular fiber groups show higher reactions than in the other fiber groups in the normal condition (Figs. 6, 7, 8, 9 and 10).3. The reactions of alkaline phosphatase of the cementum consist of those of cementoblasts, cementum matrix and cementum corpuscle (Figs. 3, 4, and 5). The enzymatic activities of cementoblasts are almost similar to their neighbouring fibroblasts (Figs. 1 and 2). There is no difference between the cementoblasts on the surface of cellular cementum and the acellular cementum (fibrous cementum) at all (Figs. 1 and 2).The enzyme is not found in the matrix of acellular (fibrous) cementum, but it is, occasionally, found moderate at the junction of the cementum and the periodontal membrane, and just a bit in the cemento-dentin junction (Fig. 2).In the cellular cementum, the newly formed matrix (cementoid) on the superficial layer shows a slight reaction, but this reaction decreases gradually as it reaches deeper layers, and then disappears entirely. The reactions of the cementum corpuscles consist of the reactions of cementocytes and those of the wall and processes of cementum lacuna. Their reactions prove highest in the superficial zone of cementum, and decrease as they go downwards to deeper layers. Several cementum corpuscles neighbouring the cemento-dentin junction, occasionally, show however moderate reactions of the enzyme (Figs. 1, 3, 4 and 5).4. The reactions of the alveolar bone consist of three kinds of reactions: those, of the osteoblasts, of the bony matrix, and, of the bone corpuscles. By the side of new bone formation, such as the alveolar crest of young rats, the osteoblasts and their surrounding fibers, show very intensive reactions in the enzyme. Newly formed bony matrix and the osteocytes contain a considerable amount of the enzyme, but it gradually decreaes as they run downwards to deeper layers, and disappear in some portions (Figs. 2, 8 and 10). On the surface of the bone which is now not being formed, the fibers and cells of its surrounding connective tissues (periostium) also considerably react. while superficial bony matrix and osteocytes do slightly (Figs. 2, 3 and 4).The intensity of reactions of the osteoblasts and the bony matrix, and their surrounding fibroblasts and fibers are generally more conspicuous as compared with that of the cementoblasts, the cementum matrix, and their surrounding fibroblasts and fibers