Krull C E
Biological Sciences, University of Missouri-Columbia, 108 Lefevre, 65211, Columbia, MO, USA.
Mech Dev. 2001 Jul;105(1-2):37-45. doi: 10.1016/s0925-4773(01)00395-1.
Avian neural crest cells migrate on precise pathways to their target areas where they form a wide variety of cellular derivatives, including neurons, glia, pigment cells and skeletal components. In one portion of their pathway, trunk neural crest cells navigate in the somitic mesoderm in a segmental fashion, invading the rostral, while avoiding the caudal, half-sclerotome. This pattern of cell migration, imposed by the somitic mesoderm, contributes to the metameric organization of the peripheral nervous system, including the sensory and sympathetic ganglia. At hindbrain levels, neural crest cells also travel from the neural tube in a segmental manner via three migratory streams of cells that lie adjacent to even-numbered rhombomeres. In this case, the adjacent mesoderm does not possess an obvious segmental organization, compared to the somitic mesoderm at trunk levels. Thus, the mechanisms by which the embryo controls segmentally-organized cell migrations have been a fascinating topic over the past several years. Here, I discuss findings from classical and recent studies that have delineated several of the tissue, cellular and molecular elements that contribute to the segmental organization of neural crest migration, primarily in the avian embryo. One common theme is that neural crest cells are prohibited from entering particular territories in the embryo due to the expression of inhibitory factors. However, permissive, migration-promoting factors may also play a key role in coordinating neural crest migration.
鸟类神经嵴细胞沿着精确的路径迁移到其目标区域，在那里它们形成各种各样的细胞衍生物，包括神经元、神经胶质细胞、色素细胞和骨骼成分。在其路径的一部分中，躯干神经嵴细胞以节段性方式在体节中胚层中导航，侵入头侧半体节，同时避开尾侧半体节。这种由体节中胚层施加的细胞迁移模式有助于外周神经系统的分节组织，包括感觉和交感神经节。在 hindbrain 水平，神经嵴细胞也以节段性方式从神经管通过与偶数菱形节相邻的三个细胞迁移流迁移。在这种情况下，与躯干水平的体节中胚层相比，相邻的中胚层没有明显的节段组织。因此，在过去几年中，胚胎控制节段性组织细胞迁移的机制一直是一个引人入胜的话题。在这里，我讨论了经典研究和近期研究的结果，这些研究已经描绘了一些有助于神经嵴迁移节段性组织的组织、细胞和分子元素，主要是在鸟类胚胎中。一个共同的主题是，由于抑制因子的表达，神经嵴细胞被禁止进入胚胎中的特定区域。然而，允许性的、促进迁移的因子也可能在协调神经嵴迁移中起关键作用。
