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Fig. 5 Pectoral fin development is severely disrupted in embryos injected with both sall1a and sall4 MO. As shown in the table, coinjection of sall1a and sall4 MOs leads to a significant increase in the most severe phenotype (no fins). Methylene Blue stained sections of the pectoral fin forming region in a wild-type embryo (A) and an embryo injected with 4 ng sall1a + 4 ng sall4 MO (B) at 48 hpf shows that a fin bud initially forms in sall1a/sall4 double morphant embryos. (C-F) Lateral views of 32 hpf pectoral fin buds in wild-type embryos (C,E) and embryos injected with 4 ng of sall1a + 4 ng of sall4 MO (D,F). At this time point, sp9 is expressed in the ectoderm of wild-type fin buds (C) but is absent in sall1a/sall4 double morphant fin buds (D). Likewise, dlx2 is present in wild-type fin bud ectoderm (E) but is absent in sall1a/sall4 double morphant fins (F). At 26 hpf (G), fgf10 expression fails to initiate in the pectoral fin primordia of sall1a/sall4 double morphant embryos (compare G with Fig. 4J).