Fig. S7

Ectopic pelvic fin-like structures are induced after implantation of an Fgf10-soaked bead into the prrx1-positive lateral plate mesoderm. (A-C) Expression of sp8, a marker for fins, in zebrafish embryos implanted with an Fgf10-soaked bead (B, C) or a PBS-soaked bead (A) in the prrx1-positive region (A, B) or in the prrx1-negative region (C) at 16 hpf (see also Materials and methods). (A′, B′, C′′) Details of the boxed regions in (A), (B) and (C), respectively. The bead is indicated by an asterisk. Arrowheads indicate ectopic sp8 expression in the induced fin-like structure (B′). Note the ectopic fin bud-like structure that formed in the body wall of zebrafish embryos implanted with an FGF-soaked bead, but not with a PBS-soaked bead, in the prrx1-positive region (A, B). However, an FGF-soaked bead implanted in the prrx1-negative region did not elicit sp8 expression (C). Ectopic sp8 expression was observed only on the line extending from the ridge of pectoral fin buds despite the position of the implanted bead (B′), suggesting that ectopic apical ridges might have been induced only in the dorsoventral boundary of the ectoderm. Scale bars: 100 μm for panels (A-C); 50 μm for panels (A′-C′).