Korte G E, Friedrich V L
Brain Res. 1979 Oct 26;176(1):3-32. doi: 10.1016/0006-8993(79)90867-9.
The superior vestibular nucleus of the cat and its primary vestibular efferents were examined by light and electron microscopy. The primary vestibular afferents branch within the nucleus in a sheet-like pattern, in the transverse plane. The dendritic fields of many secondary neurons are shaped like discs and are also oriented in the transverse plane. This relation between the primary afferents and dendritic fields may be relevant to the convergence of primary afferents innervating particular endorgans onto secondary neurons. Synaptic boutons in the SV were divided into 3 putative types on the basis of the size and shape of their synaptic vesicles. The primary afferent bouton was identified by comparing the SV of the two sides after unilateral lesions of the vestibular ganglion. Its boutons contain round vesicles of 40 nm average diameter and are associated with prominent postsynaptic densities; the two other putative bouton types contain smaller, round vesicles, and pleomorphic vesicles. The primary afferent boutons largely contact proximal dendrites, their appendages, and cell somata of the secondary neurons. In animals receiving unilateral lesions of the vestibular ganglion and allowed to survive long enough for the primary afferent boutons to disappear (5--6 days), there occurs in the denervated as compared to normal SV: (1) a decrease in the fraction of the somal surface of the secondary neurons covered by boutons with small round vesicles; and (2) a decrease in the ratio: number of boutons with small round vesicles to number of boutons with pleomorphic vesicles. In addition, there appears on the lesioned side a new group of boutons with pleomorphic vesicles smaller than those in boutons from the control side. These observations suggest plastic changes in response to deafferentation, and may be related to the marked behavioral recovery which occurs within a few days after lesion of the vestibular ganglion.
采用光镜和电镜对猫的前庭上核及其主要前庭传出纤维进行了研究。主要前庭传入纤维在核内呈片状分支，位于横切面上。许多次级神经元的树突野呈圆盘状，也位于横切面上。初级传入纤维与树突野之间的这种关系可能与支配特定终器的初级传入纤维向次级神经元的汇聚有关。根据突触小泡的大小和形状，将前庭上核中的突触小体分为3种假定类型。通过比较前庭神经节单侧损伤后两侧的突触小泡，确定了初级传入小体。其小体含有平均直径为40nm的圆形小泡，并伴有明显的突触后致密物；另外两种假定的小体类型含有较小的圆形小泡和多形性小泡。初级传入小体主要与次级神经元的近端树突、其附属物和细胞体接触。在前庭神经节单侧损伤并存活足够长时间以使初级传入小体消失（5 - 6天）的动物中，与正常前庭上核相比，去神经侧出现了以下情况：（1）被小圆形小泡小体覆盖的次级神经元胞体表面比例降低；（2）小圆形小泡小体数量与多形性小泡小体数量之比降低。此外，在损伤侧出现了一组新的小体，其多形性小泡比对照侧小体中的小泡小。这些观察结果表明，去传入后会发生可塑性变化，这可能与前庭神经节损伤后数天内出现的明显行为恢复有关。
