Fig. 4. Wnt11 activity is required for neural crest migration. (A) 1 ng of Wnt11 or 2 ng of its dominant-negative mRNA were injected in one animal blastomere of an eight-cell embryo. (B-G) Embryos were cultured until the premigratory (B,D; indicated as stage 17) or migratory (C,E,G; indicated as stage 24) neural crest stages, when the expression of Slug was analyzed. All of the embryos are shown in dorsal view, anterior to the top. The injected side is indicated by a white arrowhead. Normal neural crest migration is indicated by red arrowheads. (B,C) Wnt11 overexpression. (B) 90% of embryos showed normal Slug expression, n=55. (C) 30% of embryos showed inhibited neural crest migration, n=55. (D,E) Expression of dominant-negative Wnt11. (D) 90% of embryos showed normal Slug expression, n=65. (E) 35% of embryos showed inhibited neural crest migration; n=65. (F) Summary of inhibition of neural crest migration after injecting Wnt11 (w11), dominant-negative Wnt11 (dnw11), or both (w11+dnw11). (G) Co-injection of Wnt11 and its dominant-negative form. 90% of embryos showed normal neural crest migration, n=50.