Fig. 1

Inhibition of Fgf signaling with SU5402 prevents formation of the corpuscles of Stannius (CS).

(A) Embryos were treated with the Fgf inhibitor SU5402 (25 ​μM) from 24 to 25 hpf or from 48 to 49 hpf. The CS formation and the stc1 expression were scored 24 ​h later, at 48 and 72 hpf, respectively. (B) An example of a control cdh17:GFP transgenic embryo at 48 hpf. Arrows point to properly formed CS. (C) An example of an embryo treated with SU5402 at 24 hpf, in which CS formation could not be detected at 48 hpf. (D) Inhibition of Fgf signaling with SU5402 (25 ​μM) from 24 to 25 ​h post fertilization (hpf) significantly reduced the number of embryos with formed CS, scored at 48 hpf (p ​< ​0.001, Cochran-Mantel-Haenszel test). The treatment from 48 to 49 hpf had no effect. The numbers of scored embryos are shown within each bar. (E) Examples of embryos treated with SU5402 at 24 hpf with normal (top), strongly reduced (middle) or absent (bottom) stc1 expression at 48 hpf. (F) Examples of embryos treated with SU5402 at 48 hpf with normal (top), strongly reduced (middle) or absent (bottom) stc1 expression at 72 hpf. (G) Examples of control embryos treated with DMSO at 24 hpf (left) and 48 hpf (right) showing normal stc1 expression at 48 and 72 hpf respectively. (H) SU5402 (25 ​μM) treatment from 24 to 25 hpf eliminated stc1 expression (stc1-the percentage of zebrafish embryos without detectable stc1 expression, stc1 red. – the percentage of embryos with reduced stc1 expression; Cochran-Mantel-Haenszel test), while treatment from 48 to 49 hpf had only a marginal effect. The numbers of scored embryos are shown within each bar.