Fgf signalling does not play a role in the determination of the proximal-distal level where the bifurcation will form. (A) Heat-shock protocol following an amputation. Transgenic hsp70:dn-fgfr1 fish were amputated at 1 segment proximal to the bifurcation (near the bifurcation) and heat-shocked at 35°C for 1 hour, during 6 days, starting at day 2 post amputation. (B) Picture of a 7 days-post-amputation regenerated caudal fin of hsp70:dn-fgfr1 transgenic fish with or without the heat-shock protocol. (C) Number of segments formed in the 3rd dorsal ray between the base of the fin and the bifurcation after one amputation near the bifurcation in heat-shocked and non-heat-shocked siblings. Dashed line represents amputation plane.