MIGRATION OF NEUROBLASTS BY PERIKARYAL TRANSLOCATION - ROLE OF CELLULAR ELONGATION AND AXONAL OUTGROWTH IN THE ACOUSTIC NUCLEI OF THE CHICK-EMBRYO MEDULLA
MIGRATION OF NEUROBLASTS BY PERIKARYAL TRANSLOCATION - ROLE OF CELLULAR ELONGATION AND AXONAL OUTGROWTH IN THE ACOUSTIC NUCLEI OF THE CHICK-EMBRYO MEDULLA
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DOI：
10.1002/cne.902970105
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发表时间：
1990-07-01
影响因子：
2.5
通讯作者：
MOREST, DK
中科院分区：
文献类型：
--
作者：
BOOK, KJ;MOREST, DK
形成大细胞核的神经母细胞是哺乳动物耳蜗腹核的鸟类同系物，通过其前导突起的生长和延伸以及通过这些突起从菱形嘴唇的基质带向听觉前庭突起的移位而迁移。用高尔基体方法原位重建鸡胚胎的迁移和早期分化的形态发生阶段。体外活细胞的荧光标记阐明了轴突生长在迁移过程中的作用。在原位，耳蜗神经纤维分支，末端有生长锥体，在E4.5-5.5进入听神经前庭原基，然后在E.5.5-6.5迁移大细胞神经母细胞。菱形唇基质层中的迁移前神经母细胞类似于原始上皮细胞，它将分支、弯曲的突起延伸成一种典型的结构--菱形轮状。迁移的大细胞神经母细胞的主导过程在基质和地幔之间的交界处形成了分叉的轴突。外侧支成为复发的同侧侧支；内侧支穿过中线，走向假定板层核区的对侧靶点。迁移性神经母细胞的胞体出现在沿迁移路线的中间位置，它们通过其前导突经轴突的径向移位，然后切向和倾斜地进入地幔地带。去往板层核的神经母细胞与大细胞神经母细胞共同迁移。胚胎6.5后，角状核神经母细胞在发育后期迁移。在体外，在神经母细胞迁移时，将无毒荧光染料(DII)注射到对侧靶区的髓质外植体中。DiI通过其内侧交叉轴突逆行标记位于基质带的迁移前大细胞神经母细胞和位于外套膜带的迁移神经母细胞胞体。外植体中存活的神经母细胞的形态与高尔基体中相应迁移阶段的神经母细胞相似。也有顺行轴突运输。这些结果表明，中枢神经系统中一组特定的神经母细胞通过核周易位和早期轴突延伸而迁移。迁移的神经母细胞的形态是这样的，简单的细胞导向器的径向排列，无论是胶质的还是其他的，都不能解释它们的结构。现有证据支持细胞伸长和核周移位是中枢神经系统神经元迁移的一般模式的命题。轴突向靶点的早期延伸可能在特定类型神经元的迁移和早期发育中发挥关键作用。
The neuroblasts forming nucleus magnocellularis, the avian homologue of the mammalian ventral cochlear nucleus, migrate by growth and elongation of their leading processes and by perikaryal translocation through these processes from the matrix zone of the rhombic lip to the acoustico-vestibular anlage. Golgi methods were used on staged chick embryos to reconstruct the morphogenetic phases of migration and early differentiation in situ. Fluorescence labeling of the living cells in vitro elucidated the role of axonal growth in the migratory process. In situ, branching cochlear nerve fibers, tipped with growth cones, enter the acousticovestibular anlage at E4.5-5.5 before migration of the magnocellularis neuroblasts at E.5.5-6.5. The premigratory neuroblasts in the matrix zone of the rhombic lip resemble primitive epithelial cells, which extend branched, curving processes into a characteristic formation, the rhombic whorl. The leading process of the migrating magnocellularis neuroblasts gives rise to a bifurcating axon at the interface between the matrix and mantle zones. The lateral branch becomes the recurrent ipsilateral collateral; the medial branch crosses the midline, heading toward the contralateral target site in the region of the presumptive nucleus laminaris. The cell bodies of the migratory neuroblasts appear in intermediate locations along the migration route as they translocate radially through their leading processes past the axonal bifurcation and then tangentially and obliquely into the mantle zone. Neuroblasts destined for nucleus laminaris migrate coicidentally with magnocellularis neuroblasts. Nucleus angularis neuroblasts migrate later in development, after E6.5. In vitro, injections of a nontoxic fluorescent dye (diI) were made into explants of the medulla in the region of the contralateral target area at the time of neuroblast migration. DiI retrogradely labeled the cell bodies of premigratory magnocellularis neuroblasts in the matrix zone and of migratory neuroblasts in the mantle zone through their medial, crossing axonal braches. The morphology of the living neuroblasts in the explants resembled that in the Golgi impregnations at the corresponding stages of migration. Anterograde axonal transport also occurred. These results demonstrate migration by perikaryal translocation and early axon extension of a specific group of neuroblasts in the central nervous system. The morphology of the migrating neuroblasts is such that a simple radial arrangement of cellular guides, glial or otherwise, would not account for their configurations. The available evidence supports the proposition that cellular elongation and perikaryal translocation constitute the general mode of neuronal migration in the central nervous system. The early extension of axons into their target sites may play a critical role in migration and early development of specific types of neurons.