Fig. 1

Expression of molecular markers in different tissue layers of swimbladder as detected by WISH. (A, B) Lateral view of hb9 expression in the swimbladder epithelium at 36 hpf (A) and 72 hpf (B). Additional domains of expression were observed in neural tube (nt) and endocrine pancreas (p). White arrows in (B) indicate the primordium of anterior chamber. (C) Epithelial expression of hb9 at 72 hpf shown in cross section. (D, E) Lateral view of fgf10a expression in the mesenchyme of the swimbladder at 48 hpf (D) and at 72 hpf (E). fgf10a expression was observed in fin buds (fb) starting from 48 hpf (D) and in anterior gut starting from 72 hpf (E). (F) Mesenchymal expression of fgf10a at 72 hpf shown in cross section. (G, H) Lateral view of acta2 expression in the mesenchyme at 65 hpf (G) and 72 hpf (H). (I) Mesenchymal expression of acta2 at 72 hpf shown in cross section. (J,K) Lateral view of anxa5 expression in the swimbladder at 60 hpf (J) and 72 hpf (K). (L) Expression of anxa5 at 72 hpf shown in cross section. Expression of anxa5 was observed strongly in the outer mesothelium (o) of the swimbladder starting from 60 hpf and weakly in the epithelium (e). (M) Two-colour WISH detection of hb9 (blue) and anxa5 (red) expression in the epithelium and outer mesothelium, respectively (cross section, 72 hpf). (N) Two-colour WISH detection of acta2 (blue) and anxa5 (red) expression in the mesenchymal and outer mesothelial layers, respectively (cross section, 72 hpf). Abbreviations: e, epithelium; fb, fin bud; g, gut; m, mesenchyme; n, notochord; o, outer mesothelium; p, pancreas; pd, pneumatic duct; oe, oesophagus; ph, pharynx; s, somites; sb, swimbladder. Scale bars: 250 mm in whole mount and 100 μm in cross sections.