猫外侧颈核内脊颈纤维终末与颈丘脑投射神经元间的突触联系

本实验采用顺行溃变和ＨＲＰ逆行追踪结合的方法研究了猫脊颈丘脑通路在外侧颈核水平的突触联系。在脊髓颈段刀切损毁一侧背外侧索后将ＨＲＰ注射于对侧丘脑腹后外侧核。在电镜下于损毁同侧的外侧颈核内可见到下列突触联系：（１）溃变的轴突终末与ＨＲＰ标记的树突形成的轴—树突触；（２）溃变的轴突终末与标记的神经元胞体形成的轴—体突触；（３）溃变的轴突终末及正常的轴突终末与标记的中央树突形成的汇聚型突触复合体；（４）溃变的轴突终末与非标记的神经元树突和胞体形成的轴—树和轴—体突触；（５）正常轴突终末与标记的神经元树突和胞体形成的轴—树和轴—体突触。此外，在正常的神经元成分之间还可见到许多类型的突触。

THE SYNAPTIC CONNECTIONS BETWEEN THE SPINAL AFFERENTS AND CERVICOTHALAMIC PROJECTING NEURONS iN THE LATERAL CERVICAL NUCLEUS OF THE CAT

The synaptic relationship between the spinal afferents and cervicothalamic projecting neurons (CPNs) in the lateral cervical nucleus (LCV) was studied by combined anterograde degenerating and retrograde HRP transport methods. After mechanical ]esions of the spinocervical fibers at the 4th～5th cervical spinal segments the HRP was injected into the contralateral ventroposterolateral thalamic nucleus from zero to two days later in 9 cats. Two days later the animals were perfused and the sections containing the LCN were prepared for electron microscopy. With electron microscope the following synapses were observed in the LCN:(1)Degenerating spinal afferent terminals (DSTs) make axo-dendritic synapses with HRP labelled CPNs' dendrites;(2)DSTs make axo-somatic synapses with HRP labelled CPNs' bodies; (3) DSTs and normal axonal terminals constitute synaptic complexes with the HRP labelled central dendrites; (4) DSTs make axo-dendritic and axo-somatic synapses with unlabelled dendrites and neuronal bodies; (5)normal axonal terminals make axo-dendritic and axo-somatic synapses with HRP labelled CPNs'dendrites and bodies. This result shows that the synaptic connections of the spino-cervico-thalaic pathway in the LCN mainly are direct monosynaptic ones. It needs to be confirmed whether there exist the indirect plysynaptic connections in the pathway.