Golden J A, Zitz J C, McFadden K, Cepko C L
Department of Pathology, Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, 19104, USA.
Development. 1997 Sep;124(18):3525-33. doi: 10.1242/dev.124.18.3525.
We previously reported that retrovirally marked clones in the mature chick diencephalon were widely dispersed in the mediolateral, dorsoventral and rostrocaudal planes. The current study was undertaken to define the migration routes that led to the dispersion. Embryos were infected between stages 10 and 14 with a retroviral stock encoding alkaline phosphatase and a library of molecular tags. Embryos were harvested 2.5-5.5 days later and the brains were fixed and serially sectioned. Sibling relationships were determined following PCR amplification and sequencing of the molecular tag. On embryonic day 4, all clones were organized in radial columns spanning the neuroepithelium, which was composed primarily of a ventricular zone at this age. No tangential migration was seen in the ventricular zone. On embryonic day 5, most clones remained radial with many cells located in the ventricular zone; however, a few clones had cells migrating perpendicular to the radial column, in either a rostrocaudal or dorsoventral direction. The tangential migration began just beyond the basal limit of the ventricular zone. On embryonic days 6 and 7, many clones had cells migrating perpendicular to the radial column, which spanned from the ventricular to the pial surface. The migrating cells appeared to be aligned along axes that were perpendicular to the radial column. Using a combination of DiI tracing, immunohistochemistry and electron microscopy, we have determined that axonal tracts are present and are aligned with the migrating cells, suggesting that they support the non-radial cell migration. These data indicate that migration along pathways independent of radial glia occur outside of the ventricular zone in more than 50% of the clones in the chick diencephalon.
我们之前报道过，成熟鸡间脑中经逆转录病毒标记的克隆在内外侧、背腹侧和前后轴平面上广泛分散。本研究旨在确定导致这种分散的迁移途径。在第10至14阶段的胚胎中用编码碱性磷酸酶和分子标签文库的逆转录病毒储备液进行感染。2.5 - 5.5天后收获胚胎，将大脑固定并进行连续切片。通过对分子标签进行PCR扩增和测序来确定同胞关系。在胚胎第4天，所有克隆都排列在跨越神经上皮的放射状柱中，此时神经上皮主要由室管膜区组成。在室管膜区未观察到切向迁移。在胚胎第5天，大多数克隆仍呈放射状，许多细胞位于室管膜区；然而，少数克隆有细胞垂直于放射状柱迁移，方向为前后或背腹方向。切向迁移恰好在室管膜区的基底界限之外开始。在胚胎第6天和第7天，许多克隆有细胞垂直于从室管膜表面延伸至软脑膜表面的放射状柱迁移。迁移的细胞似乎沿着与放射状柱垂直的轴排列。通过结合DiI示踪、免疫组织化学和电子显微镜，我们确定轴突束存在且与迁移细胞对齐，这表明它们支持非放射状细胞迁移。这些数据表明，在鸡间脑超过50%的克隆中，沿着独立于放射状胶质细胞的途径的迁移发生在室管膜区之外。
