猫颈外侧核内颈丘脑投射神经元的超微结构及其突触联系

猫颈外侧核接受来自同侧脊髓后角的脊颈束 ,其传出纤维投射至对侧的丘脑腹后外侧核。该通路与传导皮肤的伤害性信息有关。本文采用 HRP逆行追踪技术 ,在电镜水平研究了猫颈外侧核内颈丘脑投射神经元的超微结构及其突触联系。将 HRP注入猫左侧丘脑腹后外侧核 ,经颈总动脉灌流固定 ,TMB法呈色反应。选取右侧颈外侧核内有 HRP标记的细胞制备电镜标本 ,透射电镜观察。结果发现 ,颈外侧核内出现大、中型 HRP标记神经元 ,细胞核为卵圆形 ,可见核仁 ,胞浆丰富 ,含有多量的线粒体等细胞内器 ,HRP反应产物散在于其中。在颈丘脑投射神经元胞体的周围见有 HRP标记的树突以及非标记的轴突、神经元胞体及树突。 HRP标记的颈丘脑投射神经元作为突触后成分与其他成分形成轴 -树突触 ,轴 -体突触 ,轴 -轴 -体突触及轴 -树突触复合体。这些结果提示 :颈丘脑投射神经元接受广泛的传入联系

THE ULTRASTRUCTURE AND SYNAPTIC CONNECTIONS OF THE CERVICOTHALAMIC PROJECTING NEURONS IN THE LATERAL CERVICAL NUCLEUS OF CAT

The lateral cervical nucleus (LCN) of the cat receives the spinocervical tract originated from the ipsilateral dorsal horn. Its efferent fibers project to the contralateral thalamic ventral posterior lateral nucleus (VPL). This closed circuit is related to cutaneous noxious information. Using horseradish peroxidase (HRP) retrograde tracing method, the ultrastructure and synaptic connections of the cervicothalamic projecting neurons (CTPN) in the LCN of the cat were investigated under electron microscope. HRP was injected into cats' left thalamic VPL. The animals were perfused for fixation through common carotid artery, and TMB method was used for staining. Electron microscopic preparation was made from HRP lalelled cellular sections in the right LCN, and observed by transmission electron microscope. There were large or medium sized neurons labelled by HRP in the LCN. The nucleus were ovoid shaped and nucleolus were clear. In the cytoplasm, there are rich mitochondria, etc. HRP products were scattered inside the cytoplasm. Around the CTPN, there were HRP labelled dendrites and unlabelled axises somas and dendrites. As the postsynaptic component, the HRP labelled CTPN formed axo dendritic, axo somatic and axo axo somatic synapses with the other portions. The results indicate that CTPN receives a broad afferent projection.