Fig. 6

Effect of tgfβ3 knockdown and over-expression on induction and migration of neural crest cells. Whole-mount lateral (A–D, I–L, Q–T) and dorsal (E–H, M–P, U–X), and flat-mount lateral (Y–AB) views are shown. Expression of the pre-migratory neural crest markers foxd3 and sox10 was similar in the uninjected (inset in A, E, inset in I, M), STD-MO injected (inset in B, F, inset in J, N), and tgfβ3 over-expressing (inset in D, H, inset in L, P) 7-somite stage embryos. In the i1e2 + e1i1 double knockdown morphants, however, a reduction in expression domain at the anterior region of the bilateral rows of pre-migratory neural crest cells (arrow) was observed (inset in C, G, inset in K, O). Expression of the migratory neural crest marker dlx2a was similar in the uninjected (Q, U, Y) and STD-MO injected (R, V, Z) embryos at the 14-somite stage. In the double knockdown morphant (S, W, AA), dlx2 expression is visibly reduced in both intensity and domain, in all three neural crest streams especially around the anterior neural crest region of S1 (arrowhead) and S2. The tgfβ3 over-expressing embryo (T, X, AB) exhibits only a mild reduction in dlx2a expression. Arched lines demarcate posterior boundary of eye primordia. Arrows indicate anterior boundary of pre-migratory neural crest cells. Arrowheads indicate anterior boundary of neural crest stream 1. ov, otic vesicle; S1–S3, neural crest streams 1–3. Black horizontal scale bars, 200 μm.