Baker C V, Bronner-Fraser M
Division of Biology, Beckman Institute 139-74, California Institute of Technology, Pasadena 91125, USA.
Mech Dev. 1997 Dec;69(1-2):13-29. doi: 10.1016/s0925-4773(97)00129-9.
The neural crest and cranial ectodermal placodes are traditionally thought to be unique to vertebrates; however, they must have had evolutionary precursors. Here, we review recent evidence suggesting that such ancestral cell types can be identified in modern non-vertebrate chordates, such as amphioxus (a cephalochordate) and ascidians (urochordates). Hence, migratory neuroectodermal cells may well have been present in the common ancestor of the chordates, such that the possibility of their existence in non-chordate deuterostomes (hemichordates and echinoderms) must also be considered. Finally, we discuss the various non-neuronal cell types produced by the neural crest in order to demonstrate that it is plausible that these different cell types evolved from an ancestral population that was neuronal in nature.
传统上认为神经嵴和颅外胚层基板是脊椎动物所特有的；然而，它们必定有进化上的前身。在这里，我们回顾最近的证据，这些证据表明在现代非脊椎脊索动物，如文昌鱼（头索动物）和海鞘（尾索动物）中可以识别出此类祖先细胞类型。因此，迁移性神经外胚层细胞很可能在脊索动物的共同祖先中就已存在，这样一来，也必须考虑它们存在于非脊索后口动物（半索动物和棘皮动物）中的可能性。最后，我们讨论了神经嵴产生的各种非神经元细胞类型，以证明这些不同的细胞类型从本质上是神经元的祖先群体进化而来是合理的。
