Cell death delineates axon pathways in the hindlimb and does so independently of neurite outgrowth.
Cell death delineates axon pathways in the hindlimb and does so independently of neurite outgrowth.
复制标题
细胞死亡描绘了后肢的轴突通路，并且独立于神经突的生长。
DOI：
10.1016/0012-1606(88)90351-x
复制
发表时间：
1988
影响因子：
2.7
通讯作者：
Pokrzywinski,JA
中科院分区：
文献类型：
--
作者：
Tosney,KW;Schroeter,S;Pokrzywinski,JA
我们希望知道，在后肢中生长的神经前端附近观察到的细胞死亡和吞噬作用是否描绘了轴突通路，如果是这样，细胞是否仅在生长锥存在的情况下死亡。我们单侧切除腰骶神经管，重建神经突开始定植于大腿时的形态。在对照组的肢体中，感觉和运动神经通路与吞噬作用的位点相吻合，包括那些尚未被生长锥定殖的通路。例如，吞噬细胞聚集在一天后形成肌肉神经的肌肉块内的病灶处。然而，在邻近的非通路区域，如后巩膜或背侧和腹侧的神经丛区域，轴突只向后延伸，他们没有看到。吞噬细胞也出现在可能无法接近生长锥的特定区域，因为它们距离通路太远（即，附属于顶端外胚层嵴）或表达可抑制轴突前进的前软骨组织的典型物质。在实验肢体中，我们保守估计神经突生长减少到不到十分之一（神经突只有在电子显微镜下可见）或不到正常的三分之一。生长延伸到远端，在一半的情况下，运动神经支配被完全废除。尽管神经突生长的广泛减少，吞噬细胞的分布是无法区分的，从对照侧。此外，吞噬细胞的数量没有显著差异。我们的结论是，细胞死亡划定轴突通路非常好，这样做没有与生长锥的相互作用，这是一个独立的特性的轴突通路，并可能直接或间接重要的轴突寻路。这是第一次识别的特点，前瞻性的神经通路在后肢。
We wished to know whether the cell death and phagocytosis seen near the outgrowing nerve front in the hindlimb delineate axon pathways and, if so, whether the cells died only in the presence of growth cones. We unilaterally deleted the lumbosacral neural tube and reconstructed the patterns of neurite outgrowth and phagocytes during the stage when neurites first begin to colonize the thigh. In the control limbs, sensory and motor nerve pathways coincided with sites of phagocytosis, including those pathways that had yet to be colonized by growth cones. For instance, phagocytes were clustered at foci within the muscle masses where muscle nerves form a day later. However, they were not seen in adjacent, nonpathway regions such as posterior sclerotome or dorsal and ventral to the region of the plexus in which axons extend only posteriorly. Phagocytes were also seen in defined regions that are probably inaccessible to growth cones because they are too distant from pathways (i.e., subjacent to the apical ectodermal ridge) or express substances that are typical of precartilagenous tissues which may prohibit axon advance. In the experimental limbs, we conservatively estimated that neurite outgrowth was reduced to less than one-tenth (neurites were visible only with electron microscopy) or less than one-third of normal. Outgrowth extended less far distally and, in half the cases, motor innervation was completely abolished. Despite the extensive reduction in neurite outgrowth, the distribution of phagocytes was indistinguishable from that of the control side. Furthermore, the number of phagocytes did not differ significantly. We conclude that cell death delineates axon pathways remarkably well and does so without an interaction with growth cones; it is an independent characteristic of the axonal pathways and may be directly or indirectly important to axonal pathfinding. This is the first identification of a feature that characterizes prospective nerve pathways in the hindlimb.