Nadol J B
Laryngoscope. 1983 Jun;93(6):780-91. doi: 10.1288/00005537-198306000-00015.
Study of the anatomy of the cochlea, and in particular the morphology of synaptic relationships between hair cells and cochlear neurons, is essential for elucidation of the mechanisms of transduction of mechanical acoustic signals into electrical neural events. Because considerable gaps remain in our understanding of the microscopic anatomy of these synapses, particularly in the human, a reconstruction of the neural pole of outer hair cells of the human organ of Corti was performed. The data are based on 577 serial sections from the basal turn and 368 sections from the middle turn. This provided complete data on 11 and partial data on 9 outer hair cells. Terminal size of afferent fibers on outer hair cells was much more uniform than that found at the base of inner hair cells. Only small bouton-like terminals were found. Branching of afferent fibers was also seen at the base of outer hair cells. Each outer hair cell received approximately two to eight afferent nerve terminals. Multiple synaptic contacts between a single afferent terminal and an outer hair cell were common. Junctional membrane specialization consisted of synapses, desmosomes, coated vesicles and arrays of microtubules and membrane cisternae. Specialization at synapses consisted of asymmetrical membrane thickening. At outer hair cells the presynaptic membrane was thicker than the postsynaptic membrane. At inner hair cells the converse was true. At outer hair cells 35% of synapses had presynaptic bodies, compared to 83% of synapses at inner hair cells. Reciprocal synapses, with both hair cell to neuron and neuron to hair cell polarities, were found only on outer hair cells. Vesiculated efferent terminals were common at the base of outer hair cells. Both axosomatic and axodendritic efferent synapses were found. In addition, the same efferent fibers were found to synapse both on an outer hair cell and on an afferent dendrite. One example of a probable dendro-dendritic synapse in the outer spiral bundle is presented.
对耳蜗解剖结构的研究，尤其是毛细胞与耳蜗神经元之间突触关系的形态学研究，对于阐明机械声信号转化为电神经活动的机制至关重要。由于我们对这些突触的微观解剖结构，尤其是人类的相关结构的理解仍存在相当大的差距，因此对人类柯蒂氏器外毛细胞的神经极进行了重建。数据基于来自基底转的577个连续切片和来自中转的368个切片。这提供了11个外毛细胞的完整数据和9个外毛细胞的部分数据。外毛细胞上传入纤维的终末大小比在内毛细胞基部发现的要均匀得多。只发现了小的纽扣状终末。在外毛细胞基部也可见传入纤维的分支。每个外毛细胞大约接受两到八个传入神经终末。单个传入终末与一个外毛细胞之间的多个突触接触很常见。连接膜特化包括突触、桥粒、被膜小泡以及微管和膜池阵列。突触特化包括不对称的膜增厚。在外毛细胞，突触前膜比突触后膜厚。在内毛细胞则相反。在外毛细胞，35%的突触有突触前小体，而在内毛细胞这一比例为83%。仅在外毛细胞上发现了具有毛细胞到神经元和神经元到毛细胞极性的相互突触。泡状传出终末在外毛细胞基部很常见。发现了轴体和轴树突传出突触。此外，发现同一传出纤维既与外毛细胞突触，也与传入树突突触。展示了外螺旋束中一个可能的树突 - 树突突触的例子。
