Rodríguez-Gallardo L, Climent V, Garciá-Martínez V, Schoenwolf G C, Alvarez I S
Departamento de Ciencias Morfológicas y Biología Celular y Animal, Universidad de Extremadura, Badajoz, Spain.
Int J Dev Biol. 1997 Oct;41(5):715-23.
Fibroblast growth factors (FGFs) are known to be involved mainly in mesoderm formation in Xenopus embryos but their participation in other inductive mechanisms such as neural induction has not been clearly established and is now under study. Here, we provide evidence that targeted over-expression of members of this family of growth factors in the periphery of full-length primitive streak chick embryos produces the formation of ectopic neural cells that are able to differentiate into neurons. The supernumerary neural plate obtained derives from the epiblast layer of the blastoderm and show signs of neural differentiation 24 h after the application of FGF. We have used cell labeling and have examined the expression of mesodermal markers to ascertain how this expansion of the neural forming region of the epiblast takes place. We conclude that the new neural cells formed are originated in the region of the epiblast fated to be epithelia and that the induction of the ectopic neural tissue is not mediated by an increase, migration or new formation of axial mesoderm. This strongly suggests that FGF is acting directly on epiblast cells, changing their fate from epidermal ectoderm to neural ectoderm. Therefore, our results show that FGF can induce neural ectoderm when acting on still uncommitted cells and, therefore, it is a putative candidate for acting in normal neural induction during development.
成纤维细胞生长因子（FGFs）已知主要参与非洲爪蟾胚胎的中胚层形成，但它们在其他诱导机制（如神经诱导）中的作用尚未明确确立，目前仍在研究中。在此，我们提供证据表明，在全长原条鸡胚胎的周边靶向过表达该生长因子家族的成员会产生异位神经细胞，这些细胞能够分化为神经元。所获得的额外神经板源自胚盘的上胚层，在应用FGF后24小时显示出神经分化的迹象。我们使用了细胞标记并检测了中胚层标记物的表达，以确定上胚层神经形成区域的这种扩展是如何发生的。我们得出结论，新形成的神经细胞起源于注定要成为上皮细胞的上胚层区域，并且异位神经组织的诱导不是由轴向中胚层的增加、迁移或新形成介导的。这强烈表明FGF直接作用于上胚层细胞，将它们的命运从表皮外胚层转变为神经外胚层。因此，我们的结果表明，FGF在作用于尚未定向的细胞时可以诱导神经外胚层，因此，它是在发育过程中正常神经诱导中发挥作用的一个假定候选因子。
