Ichikawa H, He Y F, Sugimoto T
Second Department of Oral Anatomy, Okayama University Dental School, Japan.
Somatosens Mot Res. 1998;15(2):128-33. doi: 10.1080/08990229870853.
S100-immunoreactivity (ir) was examined in tooth pulp primary neurons of the rat. An immunofluorescence method demonstrated that the molar tooth pulp contained S100-immunoreactive (ir) nerve fibers. In the root pulp, pulp horn and roof of the pulp chamber, S100-ir smooth and varicose fibers ramified and formed subodontoblastic nerve plexuses. All the fibers became varicose at the base of the odontoblastic layer and extended to the odontoblastic layer. Some varicose endings could be traced into the dentin. The trigeminal neurons retrogradely labeled with fluorogold (FG) from the first and second maxillary molar tooth pulps exhibited S100- and parvalbumin-ir. Approximately 60% and 24% of the labeled cells were ir for S100 and parvalbumin, respectively. Virtually all parvalbumin-ir FG-labeled cells showed S100-ir, while 40% of S100-ir ones coexpressed parvalbumin-ir. An immunoelectron microscopic method revealed that all myelinated axons and half of the unmyelinated axons in the root pulp contained S100-ir. In the odontoblastic layer, predentin and dentin, S100-ir neurites lost the Schwann cell ensheathment and made close contact with cell bodies and processes of odontoblasts. The odontoblastic layer also contained parvalbumin-ir neurites. These neurites were devoid of the Schwann cell ensheathment and in close apposition to cell bodies and processes of odontoblasts. S100-ir pulpal axons seemed to be insensitive to repeated neonatal capsaicin treatment. This study suggests that S100-ir tooth pulp primary neurons are mostly myelinated and that S100-ir unmyelinated axons in the root pulp are preterminal segments of myelinated stem axons.
对大鼠牙髓初级神经元中的S100免疫反应性（ir）进行了检测。免疫荧光法显示，磨牙牙髓含有S100免疫反应性（ir）神经纤维。在根髓、髓角和髓室顶部，S100免疫反应性的光滑和曲张纤维分支并形成成牙本质细胞下神经丛。所有纤维在成牙本质细胞层底部变成曲张状，并延伸至成牙本质细胞层。一些曲张末梢可追踪到牙本质中。用荧光金（FG）从第一和第二上颌磨牙牙髓逆行标记的三叉神经元显示出S100和小白蛋白免疫反应性。分别约60%和24%的标记细胞对S100和小白蛋白呈免疫反应性。几乎所有小白蛋白免疫反应性的FG标记细胞都显示S100免疫反应性，而40%的S100免疫反应性细胞共表达小白蛋白免疫反应性。免疫电子显微镜方法显示，根髓中所有有髓轴突和一半无髓轴突含有S100免疫反应性。在成牙本质细胞层、前期牙本质和牙本质中，S100免疫反应性神经突失去雪旺细胞包被，并与成牙本质细胞的细胞体和突起紧密接触。成牙本质细胞层也含有小白蛋白免疫反应性神经突。这些神经突没有雪旺细胞包被，与成牙本质细胞的细胞体和突起紧密相邻。S100免疫反应性牙髓轴突似乎对新生期反复辣椒素处理不敏感。本研究表明，S100免疫反应性牙髓初级神经元大多为有髓，根髓中S100免疫反应性无髓轴突是有髓主干轴突的终末前节段。
