Fig. 2

Evx1 is required for joint formation in dermoskeleton but not bony ray bifurcation. A–L: Lateral views of heterozygous sibling (A,C,E,G,I) and evx1 mutant (B,D,F,H,J–L) adult zebrafish (A–H,K,L) and 28 days postfertilization (dpf) larvae (I,J). A–F: Adult zebrafish in the TL background (which includes the longfin mutation). For a similar analysis in the AB background, please see Supp. Figure S1. C–L: Alcian blue/Alizarin red staining of caudal fins. Anterior left and dorsal top. B,D: evx1 mutants still form fins, but these fins often exhibit structural damage. F,J: evx1 mutants lack dermoskeletal joints. Size differences in (E) and (F) reflect different ray thicknesses along the proximo-distal fin axis. I,J: By 28 dpf, WT larvae have developed 4–5 joints (I) while joints are completely absent in mutants (J). H: Fin ray bifurcations still form in evx1 mutants. G: Note that bifurcations of WT rays start at joints (arrow). K,L: Bone fractures and irregular bone structures in evx1 mutants. Scale bar = 1.2 cm in A,B, 1 mm in C,D, 140 μm in E,F, 100 μm in G–J, 200 μm in K, 260 μm in L.