sall4 is required for FGF signalling in the developing pectoral fins. Comparison of gene expression patterns in wild-type (A,C,E,G,I,K) and sall4 morphant pectoral fins (B,D,F,H,J,L). fgf10 expression in the pectoral fins at 30 hpf (A) is reduced in sall4 morphant embryos (B), as highlighted by the red arrows. fgf10 expression at 40 hpf (C) is reduced in sall4 morphant pectoral fins (D). This reduction is most pronounced in the anterior fin bud. At 40 hpf, fgf24 is detected only in the ectoderm (E) but is absent in sall4 morphant fin buds (F). dlx2 is expressed in the fin bud ectoderm at 40 hpf (G). In sall4 morphant embryos, dlx2 expression is absent in the anterior fin bud ectoderm (H, black arrowhead) but retained in the posterior (red arrowhead). sp9 is also expressed in the fin bud ectoderm at 40 hpf (I) but is downregulated in the anterior ectoderm of sall4 morphant fin buds (J, black arrowhead) and retained in the posterior (red arrowhead). erm is expressed in wild-type pectoral fins (K) but is reduced in sall4 morphant pectoral fins (L).
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