Loring J F, Erickson C A
Dev Biol. 1987 May;121(1):220-36. doi: 10.1016/0012-1606(87)90154-0.
Neural crest cells migrate during embryogenesis to give rise to segmented structures of the vertebrate peripheral nervous system: namely, the dorsal root ganglia and the sympathetic chain. However, neural crest cell arise from the dorsal neural tube where they are apparently unsegmented. It is generally agreed that the somites impose segmentation on migrating crest cells, but there is a disagreement about two basic questions: exactly pathways do neural crest cells use to move through or around somites, and do neural crest cells actively migrate or are they passively dispersed by the movement of somite cells? The answers to both questions are critically important to any further understanding of the mechanisms underlying the precise distribution of the neural crest cells that develop into ganglia. We have done an exhaustive study of the locations of neural crest cells in chick embryos during early stages of their movement, using antibodies to neural crest cells (HNK-1), to neural filament-associated protein in growing nerve processes (E/C8), and to the extracellular matrix molecule laminin. Our results show that Some neural crest cells invade the extracellular space between adjacent somites, but the apparent majority move into the somites themselves along the border between the dermatome/myotome (DM) and the sclerotome. Neural crest cells remain closely associated with the anterior half of the DM of developing somites as they travel, suggesting that the basal lamina of the DM may be used as a migratory substratum. Supporting this idea is our observation that the development of the DM basal lamina coincides in time and location with the onset of crest migration through the somite. The leading front of neural crest cells advance through the somite while the length of the DM pathway remains constant, suggesting active locomotion, at least in this early phase of development. Neural crest cells leave the DM at a later stage of development to associate with the dorsal aorta, where sympathetic ganglia form, and to associate with newly emerging fibers of the ventral root nerve, where they presumably give rise to neuronal supportive cells. Thus we propose that the establishment of the segmental pattern of the peripheral ganglia and nerves depends on the timely development of appropriate substrata to guide and distribute migrating neural crest cells during the early stages of embryogenesis.
神经嵴细胞在胚胎发育过程中迁移，形成脊椎动物外周神经系统的分段结构，即背根神经节和交感神经链。然而，神经嵴细胞起源于背神经管，在那里它们显然是不分段的。人们普遍认为体节对迁移的嵴细胞施加分段，但在两个基本问题上存在分歧：神经嵴细胞究竟通过什么途径穿过或绕过体节，以及神经嵴细胞是主动迁移还是被体节细胞的运动被动分散？这两个问题的答案对于进一步理解发育成神经节的神经嵴细胞精确分布的潜在机制至关重要。我们利用针对神经嵴细胞（HNK-1）、生长神经突起中的神经丝相关蛋白（E/C8）以及细胞外基质分子层粘连蛋白的抗体，对鸡胚中神经嵴细胞在其运动早期阶段的位置进行了详尽研究。我们的结果表明，一些神经嵴细胞侵入相邻体节之间的细胞外空间，但明显大多数沿着皮节/肌节（DM）和生骨节之间的边界进入体节本身。神经嵴细胞在迁移过程中与发育中体节的DM前半部分保持紧密联系，这表明DM的基膜可能被用作迁移基质。支持这一观点的是我们的观察结果，即DM基膜的发育在时间和位置上与嵴细胞通过体节的迁移开始相吻合。神经嵴细胞的前沿穿过体节，而DM途径的长度保持不变，这表明至少在发育的这个早期阶段存在主动运动。神经嵴细胞在发育后期离开DM，与背主动脉相关联，交感神经节在此形成，并与腹根神经的新出现纤维相关联，它们可能在此产生神经元支持细胞。因此，我们提出外周神经节和神经的分段模式的建立取决于在胚胎发育早期及时发育适当的基质，以引导和分布迁移的神经嵴细胞。
