Ralston D D, Ralston H J
J Comp Neurol. 1985 Dec 15;242(3):325-37. doi: 10.1002/cne.902420303.
This study examined the corticospinal tract in monkey by utilizing the anterograde transport of wheat germ lectin conjugated to horseradish peroxidase (WGA HRP) at the light microscopic level and the axonal transport of 3H-proteins with both light and electron microscopic autoradiographic techniques. The animals survived 3-9 days after the injections of 3H-leucine or 3H-leucine/WGA HRP into either motor or sensory cortices. With the laminar schema of Rexed as a guide to the layers of the spinal gray matter, qualitative and quantitative analyses of labeled projections of the corticospinal tract (CST) were made. With the light microscope, axons from the sensory cortex labeled with WGA-HRP could be observed in the contralateral spinal gray from lamina I to the border of laminae VI/VII, the heaviest distribution being located in medial III-VI. There was a small ipsilateral projection to V and VI. With 3H label, laminae I and II revealed few overlying silver grains; many grains overlay laminae III-VI. Projections from the motor cortex labeled with either WGA-HRP or 3H extended from the contralateral laminae III/IV border into the motor nucleus (lamina IX) and were seen to be somewhat more dense in the lateral areas of the spinal gray. The motor cortex projected heavily to ipsilateral VIII, and in sparse amounts to ipsilateral V and VI. Electron microscopy of radioactive axons from the sensory cortex to dorsal horn revealed many radioactive myelinated fibers and some labeled non-myelinated axons. Labeled terminals contacted medium to small dendrites; there were a few labeled C-type profiles in glomeruli and occasional axo-axonal or dendro-axonal contacts, the labeled cortical axons being the postsynaptic structure. In ventral horn following motor cortex injections, the labeled axons were all myelinated. The synaptic contacts were found on small, medium, and large proximal dendrites as well as on cell bodies. Labeled terminals which formed the central element in glomeruli were also seen in this region. Most of the labeled corticospinal terminals in dorsal and ventral horn contained rounded vesicles, but a significant number revealed pleomorphic vesicles. The relationship of these morphological findings to physiological studies of the CST is presented.
本研究通过在光学显微镜水平利用与辣根过氧化物酶结合的小麦胚凝集素（WGA-HRP）的顺行运输以及采用光学和电子显微镜放射自显影技术对³H-蛋白质的轴突运输，来研究猴子的皮质脊髓束。在将³H-亮氨酸或³H-亮氨酸/WGA-HRP注射到运动或感觉皮层后，动物存活3 - 9天。以Rexed的分层模式作为脊髓灰质层的指南，对皮质脊髓束（CST）的标记投射进行了定性和定量分析。在光学显微镜下，在对侧脊髓灰质从I层到VI/VII层边界可观察到用WGA-HRP标记的来自感觉皮层的轴突，最密集的分布位于内侧III - VI层。有少量同侧投射到V层和VI层。用³H标记时，I层和II层显示很少有重叠的银颗粒；许多颗粒覆盖在III - VI层。用WGA-HRP或³H标记的来自运动皮层的投射从对侧III/IV层边界延伸到运动核（IX层），并且在脊髓灰质的外侧区域似乎更密集。运动皮层大量投射到同侧VIII层，少量投射到同侧V层和VI层。对从感觉皮层到背角的放射性轴突进行电子显微镜观察发现许多放射性有髓纤维和一些标记的无髓轴突。标记的终末与中到小的树突接触；在神经小球中有一些标记的C型结构以及偶尔的轴-轴或树-轴接触，标记的皮质轴突是突触后结构。在运动皮层注射后，腹角中标记的轴突都是有髓的。在小、中、大的近端树突以及细胞体上发现了突触接触。在该区域也可见到形成神经小球中心成分的标记终末。背角和腹角中大多数标记的皮质脊髓终末含有圆形小泡，但有相当数量显示为多形性小泡。本文介绍了这些形态学发现与CST生理学研究的关系。
