Glueckert Rudolf, Pfaller Kristian, Kinnefors Anders, Rask-Andersen Helge, Schrott-Fischer Anneliese
Department of Otolaryngology, Institute of Anatomy and Histology, Medical University of Innsbruck, Innsbruck, Austria.
Audiol Neurootol. 2005 Sep-Oct;10(5):258-73. doi: 10.1159/000086000. Epub 2005 May 27.
This study was based on high-resolution SEM assessment of freshly fixed, normal-hearing, human inner ear tissue. In addition, semiquantitative observations were made in long-term deafened temporal bone material, focusing on the spiral ganglia and nerve projections, and a detailed study of the fine bone structure in macerated tissues was performed. Our main findings detail the presence of extensive bony fenestrae surrounding the nerve elements, permitting a relatively free flow of perilymph to modiolar structures. The clustering of the spiral ganglion cells in Rosenthal's canal and the detailed and intricate course of postganglionic axons are described. The close proximity of fibers to cell soma is demonstrated by impression in cell surfaces, and presence of small microvilli-like structures at the contact regions, anchoring nerve fibers to the cell wall. Extensive fenestrae and the presence of a fragile network of endosteal bony structures at the surfaces guiding nerve fibers are described in detail for the first time. This unique freshly prepared human material offers the opportunity for a detailed ultrastructural study not previously possible on postmortem fixed material and more accurate information to model electrostimulation of the human auditory nerve through a cochlear implant. On the basis of this study, we suggest that the concentration and high density of spiral ganglion cells, and the close physical interaction between neural elements, may explain the slow retrograde degeneration found in humans after loss of peripheral receptors. Moreover, the fragile bony columns connecting the spiral canal with the osseous spiral lamina may be a potential site for trauma in (perimodiolar) electrode positioning.
本研究基于对新鲜固定的、听力正常的人类内耳组织进行高分辨率扫描电子显微镜评估。此外，对长期耳聋的颞骨材料进行了半定量观察，重点关注螺旋神经节和神经投射，并对浸软组织中的精细骨结构进行了详细研究。我们的主要发现详细描述了围绕神经元件存在广泛的骨窗，使外淋巴能够相对自由地流向蜗轴结构。描述了螺旋神经节细胞在罗森塔尔管中的聚集以及节后轴突的详细而复杂的走行。通过细胞表面的压迹证明了纤维与细胞体的紧密接近，以及在接触区域存在小的微绒毛样结构，将神经纤维锚定在细胞壁上。首次详细描述了广泛的骨窗以及在引导神经纤维的表面存在脆弱的骨内膜骨结构网络。这种独特的新鲜制备的人体材料为以前在死后固定材料上无法进行的详细超微结构研究提供了机会，并为通过人工耳蜗对人类听神经进行电刺激建模提供了更准确的信息。基于这项研究，我们认为螺旋神经节细胞的集中和高密度以及神经元件之间紧密的物理相互作用，可能解释了人类在周围感受器丧失后发现的缓慢逆行性退变。此外，连接螺旋管与骨螺旋板的脆弱骨柱可能是（蜗轴周围）电极定位时的潜在创伤部位。
