The dorsolateral corticospinal tract in mice: An alternative route for corticospinal input to caudal segments following dorsal column lesions
The dorsolateral corticospinal tract in mice: An alternative route for corticospinal input to caudal segments following dorsal column lesions
复制标题
DOI：
10.1002/cne.20090
复制
发表时间：
2004-05-10
影响因子：
2.5
通讯作者：
Tessier-Lavigne, M
中科院分区：
文献类型：
--
作者：
Steward, O;Zheng, BH;Tessier-Lavigne, M
在啮齿动物中，皮质脊髓束(CST)轴突的主要分支下降到背柱的腹侧部分。然而，有一支CST轴突在背外侧柱(“皮质脊髓背外侧束”，或DLCST)下降。在这里，我们通过向感觉运动皮质注射生物素化葡聚糖胺后追踪CST投射来定义DLCST的一些特征，评估DLCST轴突和终末分支在完整小鼠和背柱主要CST轴突已被切断的小鼠中的分布。在锥体交叉处，DLCST轴突从主束发出，在脊髓延髓交界处下方的背外侧灰质中聚集成束，并在前几个颈段以逐渐向背外侧柱的轨迹投射。然后，DLCST轴突沿着背外侧柱投射到骶骨水平，形成投射到灰质的侧支。标记的DLCST轴突在颈段最丰富，多呈束状聚集，在尾段逐渐减少。对选择性损伤背柱的小鼠DLCST轴突的示踪表明，DLCST轴突广泛分布于背角和腹角，DLCST轴突侵袭的区域与主束中CST轴突支配的区域相似。在腹角的大神经元(推测为运动神经元)附近可见一些静脉曲张的DLCST轴突。大量DLCST轴突穿过中线投射到对侧灰质。因此，DLCST为CST传入尾段提供了另一种途径，这对于研究部分脊髓损伤后CST的分布和功能具有特别重要的意义。(C)2004年Wiley-Liss公司
In rodents, the main contingent of corticospinal tract (CST) axons descends in the ventral part of the dorsal column. There is, however, a contingent of CST axons that descends in the dorsolateral column (the "dorsolateral corticospinal tract," or DLCST). Here, we define some of the features of the DLCST by tracing CST projections following injections of biotinylated dextran amine into the sensorimotor cortex, assessing the distribution of DLCST axons and terminal arborizations in intact mice and in mice in which the main contingent of CST axons in the dorsal column had been transected. Axons of the DLCST diverge from the main tract at the pyramidal decussation, gather in fascicles in the dorsolateral gray matter below the spinomedullary junction, and project in a gradual trajectory laterally toward the dorsolateral column over the first few cervical segments. DLCST axons then project along the dorsolateral column to sacral levels, giving rise to collaterals that project into the gray matter. Labeled DLCST axons were most abundant in cervical segments, where they were often collected in fascicles, and progressively decreased in number in more caudal segments. Tracing of DLCST axons in mice with selective lesions of the dorsal column revealed that DLCST axons arborize extensively throughout the dorsal and ventral horns and that the overall territory that the DLCST axons invade is similar to the territory innervated by the CST axons in the main tract. Some DLCST axon arbors with varicosities are seen near large neurons in the ventral horn (presumed motoneurons). Substantial numbers of DLCST axons project across the midline to the gray matter on the contralateral side. Thus; the DLCST provides an alternate route for CST input to caudal segments, which is of particular relevance for studies of CST distribution and function following partial spinal cord injuries. (C) 2004 Wiley-Liss, Inc.