皮质脊髓束谷氨酸能投射的定性追踪——光镜和电镜研究

Qualitative Tracing of Gluamatergic Projection of Corticospinal Tract ——Light and Electron Microscopic Studies

用辣根过氧化物酶（ＨＲＰ）与免疫细胞化学结合和免疫电镜方法研究了大鼠皮质脊髓束的化学性质以及它们与脊髓神经细胞之间的超微结构关系。一侧脊髓背角或部分腹角注射ＨＲＰ后，光镜下在大鼠对侧大脑皮质第４区第Ⅳ层可见３种细胞：①谷氨酸（Ｇｌｕ）样免疫反应阳性细胞；②ＨＲＰ单标细胞；③ＨＲＰ和谷氨酸样免疫反应双标细胞。在大鼠脊髓腹角可见大量谷氨酸免疫反应阳性胞体和纤维。电镜下，在脊髓腹角内谷氨酸样免疫反应产物呈细小颗粒状沉淀，分布于树突、轴突、核周质以及星形胶质细胞内。此外，尚可见３种类型的突触：①Ｇｌｕ阴性轴突与Ｇｌｕ阳性树突构成的轴树突触；②Ｇｌｕ阳性轴突与Ｇｌｕ阴性树突构成的轴树突触；③Ｇｌｕ阳性轴突与Ｇｌｕ阴性轴突构成的轴轴突触。以上结果表明：大鼠皮质脊髓束至少有一部分纤维是谷氨酸能投射，这些纤维起自对侧大脑皮质，在脊髓内下行，主要终止于背角，部分终止于腹角。

The chemical natures of the corticospinal tract and their ultrastructural relationship with the neurons of the ventral horn of the spinal cord of rats were studied by means of HRP tracing combined with immunocytochemical and immunoelectron microscopic methods After unilateral injection of HRP into the dorsal horn or part of the ventral horn, there were three kinds of neurons appeared in the layer 4 of the area 4 of the contralateral cerebral cortex: (1) Glutamate (Glu) like immunoreacrive (LI) positive cells; (2) HRP single labeled cells; (3) HRP and Glu LI double labeled cells The latter two were much more in the cases of dorsal horn injection There were also a lot of Glu LI positive cell bodies and fibers in the ventral horn of the spinal cord Under an electron microscope, the Glu LI positive products appeared as small granular depositions existing in neural dendrites, axons, perikarya and the cytoplasm of the astrocytes In addition, there were three kinds of synapses: (1) axo dendritic synapse formed by Glu negative axon with Glu LI positive dendrite; (2) axo dendritic synapse formed by Glu LI positive axon with Glu LI negative dendrite; (3) axo axonic synapse formed by Glu LI positive axon with Glu LI negative axon The above mentioned results suggested that the corticospinal tract of rats is part at least glutamatergic which originating from the contralateral cerebral cortex, descending in the spinal cord, terminating mainly in the dorsal horn (part in the ventral horn) and indirectly regulating the motor neurons in the ventral horn by synapses interneurons formed