Fig. 5
id2a is regulated by Bmps and excluded from the ectomesenchyme.
(A–C) Colorimetric in situs show weak expression of id2a in pre-migratory CNCCs at 12 hpf (dorsal view with anterior up, arrows indicate bilateral CNCC fields) and increasing expression in non-ectomesenchyme precursors at 17.5 and 19 hpf (lateral views). (D–I) Confocal projections of fluorescent in situs show co-localization of id2a with sox10 in CNCCs at 12 hpf (D) and 14 hpf (E), as well as co-localization in the non-ectomesenchyme at 16.5 hpf (F). At 16.5 hpf, id2a is excluded from ectomesenchyme CNCCs marked by dlx2a (G) and twist1a (H), with twist1a also being expressed in head mesoderm. In sox10:Gal4VP16; UAS:Bmp4 embryos, id2a and sox10 are expressed ectopically in the ectomesenchyme (white arrows). Arrowheads indicate otic expression of sox10. Scale bars = 50 μm.