Immunohistochemical and Enzyme-histochemical studies on the cellular networks of antigen-presenting cells in the dental and periodontal tissues.

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In order to elucidate the entire biological network of antigen-pressenting cells in the oral regions, incisors and molar tooth germs of the rat and human permanent as well as decidous teeth were examined with respect to the following aspects ;1. Antigen-presenting cell network : Cellular networks of the antigen-presenting cells including macrophages were examined by neans of the double staining method with immunostaining for and anti-MHC class II antigen and enzyme histochemistry for ACPase. Dendritic cells (DC) and macrophages were discriminated in both the dental pulp and periodontal ligament (PDL), and their localization patterns demonstrated. In young animals, the dendritic cells were small in number and gradually increased as they grew. In the PDL of rat molars, the DC and osteoclasts showed distinct segregated localization. In the pulp tissues of rat and human teeth, the DC often extended long cell processes deep into the dentinal canals under physiological conditions.2. Cavity p … More reparation and dendritic cells : Early responses of DC in the dental pulp to cavity preparation was clearly demonstrated for the first time. The DC were shown to accumulate at the traumatic regions of the odontoblastic layr immediately after cavity preparaton. They remained there until the onset of the dposition of the reparative dentin. A possible role of the DC in pulp repair in addition to reception and processing of foreign antigens was suggested.3. Discrimination between the precursor cells of DC and osteoclasts : In the PDL of rat molars where physiological bone resorption proceeds at the distal face of the alveolar bone, DC predominantly located at the proximal PDL where bone formation was dominant. Orthodontic force from distal to proximal direction of the molar tooth caused different spatio-temporal arrangement of the DC in the PDL.In this experiment model, the precursor cells of the DC and osteoclasts were surveyed.4. DC in human deciduous teeth : The distribution and cytological features of DC in human deciduous teeth at different functional stages (normal, root resorption, crown resorption) were examined. The DC in the deciduous teeth often inserted cytoplasmic processes into the dentinal canals as was the case in permanent teeth. A functional correlation of the pulpal DC with cementogenesis that occasionally commenced after resorption of the crown dentin was suggested. Less