Chang C, Hemmati-Brivanlou A
Laboratory of Molecular Embryology, Rockefeller University, New York, NY 10021, USA.
J Neurobiol. 1998 Aug;36(2):128-51.
During gastrulation in vertebrates the cells of the embryonic ectoderm give rise to epidermal progenitors in the ventral side and neural progenitors in the dorsal side. Despite many years of scrutiny, the molecular basis of these important embryonic cell fate decisions have not been solved. Only recently have we witnessed swift progress in the quest for factors involved in neural and epidermal induction. Several of what seem to be bona fide in vivo neural and epidermal inducers have been cloned, and the mechanism of their functions in embryos is also beginning to be understood. These new molecular results have revolutionized our view on the patterning of embryonic ectoderm and suggest that while the induction of epidermis requires instructive inductive signals, the establishment of neural fate occurs by default when epidermal inducers are inhibited. In this review, we discuss recent advances of our knowledge on epidermal and neural induction in the context of the "default model". We will then address the process of neurogenesis as well as recent findings on neural patterning. Emphasis is placed on, but not limited to, discoveries made in Xenopus, as most of our progress in understanding the ectodermal patterning is obtained from studies using this organism.
在脊椎动物原肠胚形成过程中，胚胎外胚层细胞在腹侧产生表皮祖细胞，在背侧产生神经祖细胞。尽管经过多年的仔细研究，这些重要的胚胎细胞命运决定的分子基础仍未得到解决。直到最近，我们才在寻找参与神经和表皮诱导的因子方面取得了迅速进展。一些似乎是真正的体内神经和表皮诱导因子已被克隆，它们在胚胎中的作用机制也开始被理解。这些新的分子研究结果彻底改变了我们对胚胎外胚层模式形成的看法，并表明虽然表皮的诱导需要指导性诱导信号，但当表皮诱导因子被抑制时，神经命运的建立是默认发生的。在这篇综述中，我们将在“默认模型”的背景下讨论我们在表皮和神经诱导方面的最新知识进展。然后，我们将探讨神经发生过程以及神经模式形成的最新发现。重点将放在，但不限于，在非洲爪蟾中取得的发现，因为我们在理解外胚层模式形成方面的大部分进展都来自于使用这种生物的研究。
