Eybalin M, Parnaud C, Geffard M, Pujol R
INSERM-U.254, Montpellier, France.
Neuroscience. 1988 Jan;24(1):29-38. doi: 10.1016/0306-4522(88)90308-9.
Using an immunoperoxidase technique, we have localized by light and electron microscopy GABA-immunostained fibers within a component of the efferent innervation of the organ of Corti. At the light microscopic level, GABA-immunostained fibers were observed within the inner spiral bundle (below the inner hair cells) and the tunnel spiral bundle. The immunostaining was clearly more intense in the upper turns than in the basal turns. Mostly in the upper turns, GABA-immunostained fibers were seen crossing the tunnel of Corti to reach the outer hair cells where they formed large immunostained patches at the base of the cells. Unevenly distributed throughout these upper turns, immunostained fibers were seen climbing along the outer hair cells and traveling near the non-sensorineural Hensen's cells. The electron microscopic observations of GABA-immunostained fibers in the upper turns allowed us to identify within the inner spiral bundle vesiculated varicosities synapsing with radial dendrites connected to the inner hair cells. In the outer hair cell area, the GABA-immunostained fibers made several kinds of synaptic contacts. They included a minor population of the large axosomatic synapses with the basal pole of the outer hair cells and many axodendritic synapses with the spiral dendrites connected to these cells. Occasionally, the GABA-immunostained climbing fibers also synapsed with the outer hair cells at a supranuclear level. These result confirm previous light microscopic data dealing with the projection of the GABA-immunostained fibers along the cochlear partition. Moreover, they extend them in characterizing several kinds of GABA-immunostained synapses. These latter findings agree with previous neurochemical electrophysiological data which suggests an efferent neurotransmitter role for GABA. Nevertheless, such an existence of an efferent innervation predominantly projecting to the upper turns of the cochlea adds another criterion distinguishing the "apical" from the "basal" cochlea.
我们运用免疫过氧化物酶技术，通过光学显微镜和电子显微镜定位了柯蒂氏器传出神经支配成分内的γ-氨基丁酸（GABA）免疫染色纤维。在光学显微镜水平，在内螺旋束（内毛细胞下方）和隧道螺旋束内观察到了GABA免疫染色纤维。上半圈的免疫染色明显比基部圈更强烈。主要在上半圈，可见GABA免疫染色纤维穿过柯蒂氏隧道到达外毛细胞，在细胞基部形成大的免疫染色斑块。免疫染色纤维不均匀地分布于这些上半圈，可见它们沿着外毛细胞攀爬并在非感觉性的亨森细胞附近穿行。对上半圈GABA免疫染色纤维的电子显微镜观察使我们能够在内螺旋束内识别出与连接内毛细胞的放射状树突形成突触的囊泡状曲张体。在外毛细胞区域，GABA免疫染色纤维形成了几种突触联系。它们包括少数与外毛细胞基部极形成的大型轴体突触以及许多与连接这些细胞的螺旋状树突形成的轴突树突突触。偶尔，GABA免疫染色的攀爬纤维也会在核上水平与外毛细胞形成突触。这些结果证实了先前关于GABA免疫染色纤维沿耳蜗隔板投射的光学显微镜数据。此外，它们在表征几种GABA免疫染色突触方面对这些数据进行了扩展。这些最新发现与先前的神经化学电生理数据一致，这些数据表明GABA具有传出神经递质的作用。然而，这种主要投射到耳蜗上半圈的传出神经支配的存在增加了区分“顶端”耳蜗和“基部”耳蜗的另一个标准。
