Flumerfelt B A
J Anat. 1980 Dec;131(Pt 4):621-33.
The pattern and mode of termination of afferents to the red nucleus of the rat were investigated with the electron microscope. Lesions were placed by electrocautery in the sensorimotor cortex or were placed electrolytically in the deep cerebellar nuclei and brachium conjunctivum using a stereotaxic approach. With both types of lesion, degenerating fibres of passage, preterminal axons, and synaptic terminals were observed in greatest numbers on the third post-operative day. Following cerebellar lesions, degenerating terminals occurred on the cell bodies and proximal dendrites of large, multipolar neurons in the magnocellular portion of the red nucleus, and on intermediate and small dendrites in the parvocellular portion. It is concluded that the former are interpositus terminals while the latter are dentate (lateralis) terminals ending on rubrospinal and rubrobulbar neurons respectively. Following lesions of the sensorimotor cortex, small degenerating terminals were observed on the distal dendrites and dendritic spines of parvocellular, rubrobulbar neurons. Large terminals containing round vesicles did not undergo degeneration following either type of lesion. These findings suggest the existence of an interpositorubro-spinal pathway in which the interpositus terminals exert a strong influence on the large, caudally placed rubrospinal neurons. The background excitability of the rostrally located rubrobulbar neurons is probably regulated by the distal cortical input while the more proximally located dentate terminals probably exert a stronger discrete influence over their activity.
利用电子显微镜研究了大鼠红核传入纤维的终止模式和方式。用电烙术在感觉运动皮层制造损伤，或采用立体定位方法用电解损伤法在小脑深部核团和结合臂制造损伤。两种损伤类型在术后第三天观察到的退变纤维、终末前轴突和突触终末数量最多。小脑损伤后，退变终末出现在红核大细胞部大型多极神经元的胞体和近端树突上，以及小细胞部的中间和小型树突上。结论是前者是间位核终末，后者是齿状核（外侧核）终末，分别终止于红核脊髓神经元和红核延髓神经元。感觉运动皮层损伤后，在小细胞部红核延髓神经元的远端树突和树突棘上观察到小的退变终末。含圆形囊泡的大型终末在两种损伤类型后均未发生退变。这些发现提示存在一条间位核-红核脊髓通路，其中间位核终末对大型、位于尾部的红核脊髓神经元有强烈影响。位于头端的红核延髓神经元的背景兴奋性可能受远端皮质输入调节，而位于更靠近近端的齿状核终末可能对其活动施加更强的离散影响。
