Electron-microscopic affiliations of oxytalan fibres, nerves and the microvascular bed in the mouse periodontal ligament.

Throughout the ligament, oxytalan fibres were contiguous to myelinated nerves, unmyelinated exposed axons and free nerve endings. In the cervical and apical regions, accumulations of vessel-related simple and complex mechanoreceptor units were associated with collagen fibrils and fibres of the oxytalan system. The various receptors and nerve endings penetrated to the abluminal surface of the endothelial wall in the different categories of vessels constituting the microvascular bed. Periodontal receptors with oxytalan fibres were also present in the septal wall of dividing vessels and related to endothelial protrusions into the lumen of microvessels. Similarities existed between periodontal mechanoreceptors and baroreceptors. Anatomically, the oxytalan-fibre meshwork provided coupling between the various mechanoreceptor units in the microvascular bed. This periodontal model has morphological characteristics which support the hypothesis that the oxytalan-fibre meshwork forms part of a proprioceptor system for the regulation of vascular flow.