Fig. 6. Loss of Wnt signalling delays Raldh2 onset. (A,B) Effects of control PBS beads (A) and beads soaked in sFRP2 (B) on Raldh2 onset. Asterisk in B indicates region of Raldh2 inhibition. (C-F) Embryos cultured in ethanol control media (C,E) or media supplemented with CKI-7 (D,F). Both Lef1 and Raldh2 are downregulated by CKI-7. (G,G') After 18 hours in culture, CPM explants come to express Raldh2 in control media (G), but this is prevented by DKK1 (G'). Arrow, node; arrowhead, last somite formed. Scale bars: 100 µm in A for A-F; 50 µm in G for G,G'.