LOCALIZATION OF NADPH-DIAPHORASE ACTIVITY IN THE DENTAL-PULP, PERIODONTIUM AND ALVEOLAR BONE OF THE RAT

In this study we examined the presence and localization of nicotinamid e adenine dinucleotide phosphate diaphorase (NADPH-d) activity in the dental pulp, periodontal tissues and alveolar bone of the rat. The pre sence of NADPH-d activity was also examined in cat pulp. The rat histo chemical analysis revealed the presence of prominent NADPH-d activity both in cells of the sub-odontoblastic cell layer and in the odontobla sts, in the root as well as in the coronal pulp regions. In the pulpal horns, odontoblasts often had long processes with a high level of lab elling indicating NADPH-d activity extending through the predentin and dentin. Moreover, endothelial cells of pulpal blood vessels were posi tive for NADPH-d in both species. However, no clearcut examples were f ound of pulpal nerve fibres positive for NADPH-d in the rat or cat and denervation performed in rats did not alter the enzyme staining patte rns. In the periodontal tissue, NADPH-d activity was localized to cell s on the alveolar bone surface of the periodontal ligament and, in add ition, alveolar bone marrow crypts were filled with intensely labelled cells. In the gingival papillae, NADPH-d activity was observed in the basal cell layer of the epithelium. Endothelial cells of periodontal and gingival blood vessels showing positive staining for NADPH-d were occasionally noted.