Fig. 2

Increased Fgf signaling in the post-gastrula embryo increases cardiac cell number. (A–D) Images of representative hearts at 48 hpf in heat-shocked control sibling embryos and Tg(hsp70:ca-fgfr1)^pd3 embryos. (A,B) The hearts of heat-shocked control sibling embryos have the typical S-shaped curvature of wild-type embryos. (C,D) Hearts of Tg(hsp70:ca-fgfr1)^pd3 embryos are enlarged and dysmorphic. (E) Graph indicating the fold difference of the mean cell number of heat-shocked control sibling embryos and Tg(hsp70:ca-fgfr1)^pd3 embryos. Increasing Fgf signaling at the TB and 8s stage increases atrial and ventricular cell number, with 8s embryos being less sensitive to increased Fgf signaling than the TB stage. For cell counts, see Supplemental Table 1. Asterisks indicate that there was a statistically significant difference in cell number from the heat-shocked control sibling hearts used for these comparisons (Supplemental Table 1). Images are frontal views. Red indicates ventricle. Green indicates atrium.

Increased Fgf signaling in the post-gastrula embryo increases cardiac cell number. (A–D) Images of representative hearts at 48 hpf in heat-shocked control sibling embryos and Tg(hsp70:ca-fgfr1)^pd3 embryos. (A,B) The hearts of heat-shocked control sibling embryos have the typical S-shaped curvature of wild-type embryos. (C,D) Hearts of Tg(hsp70:ca-fgfr1)^pd3 embryos are enlarged and dysmorphic. (E) Graph indicating the fold difference of the mean cell number of heat-shocked control sibling embryos and Tg(hsp70:ca-fgfr1)^pd3 embryos. Increasing Fgf signaling at the TB and 8s stage increases atrial and ventricular cell number, with 8s embryos being less sensitive to increased Fgf signaling than the TB stage. For cell counts, see Supplemental Table 1. Asterisks indicate that there was a statistically significant difference in cell number from the heat-shocked control sibling hearts used for these comparisons (Supplemental Table 1). Images are frontal views. Red indicates ventricle. Green indicates atrium.