Figure 4

Onset of c-Raldh2 expression in the chick tail bud from HH stage 21. Lateral view of whole-mount chick tail buds at (A, F, K) HH stage 20, (B, G, L) stage 21, (C, H, M) stage 22, (D, I, N) stage 23 and (E, J, O) stage 24 analysed by in situ hybridisation with (A-E) c-Wnt3a, (F-J) c-Raldh2 and (K-O) c-Cyp26A1 to show their expression in the tail bud region. Red arrowheads show that from HH stage 20 to stage 21 there is a severe downregulation of c-Wnt3a simultaneous to an onset of c-Raldh2 in the tail bud. Lateral view of mouse tail buds at (P, T, X) E10.5, (Q, U, Y) E11.5, (R, V, Z) E12.5 and (S, W, AA) E13.5 analysed by in situ hybridisation using (P-S) m-Wnt3a, (T-W)m-Raldh2, and (X-AA)m-Cyp26A1 probes to show their expression in the tail bud region. Red arrowheads show that from E10.5 to E13.5 there is a severe downregulation of m-Wnt3a simultaneous to an onset of m-Raldh2 in the tail bud and a downregulation of m-Cyp26A1.