Fig. 1

Fig. 1 A non-PM-derived median fin fold.

a, Larval 4 dpf zebrafish possess a median PAFF (yellow arrowhead) in addition to the caudal median fin fold (cyan arrowhead). b, Confocal image of a 3 dpf Tg(tbx16l:GAL4-VP16); Tg(UAS:Kaede) embryo with PM labelled by Kaede showing PM-derived mesenchyme in the caudal median fin fold (cyan outline) but not the PAFF (yellow outline). c–e, Confocal images of pre-anal (c), ventral caudal (d) and pectoral (e) fins of the ET37 Enhancer Trap transgenic line indicating that PAFF contains morphologically comparable mesenchyme (indicated by arrowheads) to other larval fin folds. f, In situ hybridization of the fin mesenchyme marker fbln1 in both PAFF (yellow arrowhead) and caudal fin fold (cyan arrowhead) at 3 dpf. g,h, DsRed expression in mesenchyme of both pre-anal (g) and caudal (h) fin folds of the 5 dpf Tg(-5.2lyve1b:DsRed) transgenic line. i,j, Immunostaining for collagen II in 8 dpf frf mutants (j) shows loss of fibril organization compared with WT (i). Scale bars, 200 µm (a); 100 µm (b); 20 µm (c,e); 50 µm (f,g,j).