Leber S M, Sanes J R
Division of Pediatric Neurology, Washington University School of Medicine, St. Louis, Missouri 63110.
J Neurosci. 1995 Feb;15(2):1236-48. doi: 10.1523/JNEUROSCI.15-02-01236.1995.
To study the migration of chick spinal cord neurons, we labeled individual cells in the ventricular zone with recombinant retroviruses, then identified their progeny histochemically. First, we analyzed cell mixing in the ventricular zone. Some clones labeled at early neural tube stages spread widely along both the dorsoventral and rostrocaudal axes. However, clones labeled later were confined to narrow domains along both axes. These results imply that displacement of cells within the ventricular zone becomes progressively restricted. Second, we studied the migration of cells out of the ventricular zone by infecting embryos at a fixed stage and varying the time of analysis. At first, most clones consisted of radial arrays of cells, suggesting that the initial migration is predominantly radial. In many clones, however, neurons turned orthogonally from parental radial arrays and migrated along the path of circumferentially oriented axons. By hatching, clonally related cells in the gray matter were usually distributed in narrow transverse slabs, but some white matter glial cells had migrated longitudinally for up to several segments. We conclude that the dispersal of clonally related cells results from (1) early mixing of progenitors within the neural tube; (2) radial stacking of progeny in the ventricular zone; (3) migration of progeny from the ventricular zone in spoke-like routes; (4) circumferential migration of some neurons along axons; (5) short-distance dispersal of differentiating neurons; and (6) a late, longitudinal migration of glia through white matter tracts. Finally, we show that floor plate cells differ from other spinal cord cells in both their lineage and migration patterns.
为了研究鸡脊髓神经元的迁移，我们用重组逆转录病毒标记脑室区的单个细胞，然后通过组织化学方法鉴定它们的后代。首先，我们分析了脑室区的细胞混合情况。一些在神经管早期阶段标记的克隆沿着背腹轴和头尾轴广泛扩散。然而，后期标记的克隆局限于沿这两个轴的狭窄区域。这些结果表明，脑室区内细胞的位移逐渐受到限制。其次，我们通过在固定阶段感染胚胎并改变分析时间来研究细胞从脑室区的迁移。起初，大多数克隆由呈放射状排列的细胞组成，这表明最初的迁移主要是放射状的。然而，在许多克隆中，神经元从亲代放射状排列中垂直转向，并沿着周向轴突的路径迁移。到孵化时，灰质中克隆相关的细胞通常分布在狭窄的横向板层中，但一些白质胶质细胞已经纵向迁移了多达几个节段。我们得出结论，克隆相关细胞的分散是由以下原因导致的：(1) 神经管内祖细胞的早期混合；(2) 后代在脑室区的放射状堆积；(3) 后代从脑室区以辐条状路径迁移；(4) 一些神经元沿着轴突的周向迁移；(5) 分化神经元的短距离分散；以及(6) 胶质细胞通过白质束的后期纵向迁移。最后，我们表明底板细胞在谱系和迁移模式上与其他脊髓细胞不同。
