Yokoyama Takuya, Settai Kazuya, Nakamuta Nobuaki, Yamamoto Yoshio
Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan.
Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8 Ueda 3-chome, Morioka, Iwate, 020-8550, Japan.
Histochem Cell Biol. 2019 Feb;151(2):161-173. doi: 10.1007/s00418-018-1734-1. Epub 2018 Sep 22.
The morphological characteristics of baroreceptors in the rat carotid sinus were reevaluated by whole-mount preparations with immunohistochemistry for P2X3 purinoceptors using confocal scanning laser microscopy. Immunoreactive nerve endings for P2X3 were distributed in the internal carotid artery proximal to the carotid bifurcation, particularly in the region opposite the carotid body. Some pre-terminal axons in nerve endings were ensheathed by myelin sheaths immunoreactive for myelin basic protein. Pre-terminal axons ramified into several branches that extended two-dimensionally in every direction. The axon terminals of P2X3-immunoreactive nerve endings were flat and leaf-like in shape, and extended hederiform- or knob-like protrusions in the adventitial layer. Some axons and axon terminals with P2X3 immunoreactivity were also immunoreactive for P2X2, and axon terminals were closely surrounded by terminal Schwann cells with S100 or S100B immunoreactivity. These results revealed the detailed morphology of P2X3-immunoreactive nerve endings and suggested that these endings respond to a mechanical deformation of the carotid sinus wall with their flat leaf-like terminals.
利用共聚焦扫描激光显微镜，通过免疫组织化学方法对P2X3嘌呤受体进行全层标本制备，重新评估大鼠颈动脉窦压力感受器的形态学特征。P2X3免疫反应性神经末梢分布于颈动脉分叉近端的颈内动脉，尤其是在与颈动脉体相对的区域。神经末梢中的一些终末前轴突被髓鞘碱性蛋白免疫反应性的髓鞘包裹。终末前轴突分支成几个分支，在各个方向二维延伸。P2X3免疫反应性神经末梢的轴突终末呈扁平叶状，在外膜层延伸出树状或球状突起。一些具有P2X3免疫反应性的轴突和轴突终末对P2X2也有免疫反应性，轴突终末被具有S100或S100B免疫反应性的终末施万细胞紧密包围。这些结果揭示了P2X3免疫反应性神经末梢的详细形态，并表明这些末梢通过其扁平叶状终末对颈动脉窦壁的机械变形作出反应。
