Muramoto T, Takano Y, Soma K
First Department of Orthodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Yushima, Japan.
Arch Histol Cytol. 2000 Oct;63(4):369-80. doi: 10.1679/aohc.63.369.
The effect of a loss of occlusal stimuli upon the distribution and structure of the periodontal mechanoreceptors of the rat mandibular molar was examined after extracting opposing molars. The hypofunctional periodontal ligament narrowed significantly two weeks after tooth extraction, associated with an altered morphology of the Ruffini endings that showed typical dendritic profiles in normal controls. At four weeks and later periods after extraction, the Ruffini endings-including those without light microscopic changes demonstrated unusual ultrastructural features such as the eccentric localization of mitochondria along the axonal membrane and loss of other cell organelles, unusual elongation of axonal microprojections, or a deep invagination of the Schwann sheath into the axoplasm. Immunoreactivity for the growth-associated protein-43 (GAP-43) in the Ruffini endings was restricted to the Schwann element in both the normal and hypofunctional periodontal ligament, but the reaction was weaker and even negligible in some cases in the latter ligament. The present results suggest that occlusal stimuli are essential for maintaining the structural integrity of the periodontal ligament, including that of periodontal mechanoreceptors. A decreased immunoreactivity for GAP-43 in the Schwann sheaths supports the notion of a possible functional alteration in the Ruffini endings that showed no structural abnormality.
拔除对侧磨牙后，研究了咬合刺激缺失对大鼠下颌磨牙牙周机械感受器分布和结构的影响。拔牙后两周，功能减退的牙周膜显著变窄，同时鲁菲尼终末的形态发生改变，而在正常对照中其呈现典型的树突状形态。拔牙后四周及更晚时期，鲁菲尼终末（包括那些在光镜下无变化的终末）表现出异常的超微结构特征，如线粒体沿轴突膜偏心定位以及其他细胞器丢失、轴突微突起异常伸长，或施万鞘向轴质内深陷。在正常和功能减退的牙周膜中，鲁菲尼终末中生长相关蛋白43（GAP - 43）的免疫反应性均局限于施万细胞成分，但在后一种牙周膜中，该反应较弱，在某些情况下甚至可忽略不计。目前的结果表明，咬合刺激对于维持牙周膜（包括牙周机械感受器）的结构完整性至关重要。施万鞘中GAP - 43免疫反应性降低支持了鲁菲尼终末虽无结构异常但可能存在功能改变这一观点。
