Figure 4. Regulation of cell fates at the NPB by Fgf8 signaling. (A) Embryos injected with increasing amounts of Fgf8a mRNA (0.1, 0.5, 5, and 50 pg) in one blastomere at the two-cell stage and analyzed by whole-mount in situ hybridization for Pax3, Zic1, Snail2, Xhe, and Six1 expression. Pax3, Zic1, Snail2, and Xhe are expanded on the injected side by lower doses of Fgf8 (0.1 or 0.5 pg; white arrows). The expression of these genes is expanded on the contralateral side (yellow arrows) and repressed on the injected side (black arrows) for higher doses of Fgf8a (5 or 50 pg). Six1 expression is repressed unilaterally or bilaterally for intermediate (0.5 pg) or high (5 and 50 pg) doses of Fgf8a, respectively. (B) Embryos injected with Fgf8a-specific morpholino (Fgf8aMO) in the marginal zone of four-cell stage embryos exhibit a strong reduction of Pax3, Snail2, Xhe, and Six1 expression at the neurula stages (black arrows). In the absence of Fgf8a function, Zic1 anterior expression domain is expanded (white arrow), whereas posteriorly Zic1 is reduced (black arrow). In A and B, embryos hybridized with Pax3, Zic1, and Snail2 are viewed from the dorsal side, anterior to top. Anterior views are shown for embryos hybridized with Xhe and Six1. In all panels, the injected side is on the right.
Image published in: Hong CS and Saint-Jeannet JP (2007)
Copyright © 2007. Image reproduced with permission of the Publisher, American Society for Cell Biology (ASCB). This is an Open Access article.
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