Fig. 6

Misexpression of fgf8 at the end of gastrulation rescues otic induction in RA-depleted embryos, but the rescue is not maintained. (A,B) Preotic pax8 expression is expanded in transgenic hsp:fgf8 embryos (B) after misexpression of fgf8 at the end of gastrulation in comparison to non-transgenic embryos (A). (C,D) Reduced preotic pax8 expression in RA-depleted embryos (C) can be rescued by the misexpression of fgf8 at the end of gastrulation (D), as can heat-shocked transgenic hsp:fgf8 embryos with normal RA signaling (B). (E,F). Misexpression of fgf8 at late gastrulation stages (F) leads to the formation of much larger otic vesicles in comparison to their non-transgenic siblings (E). (G,H) Transgenic hsp:fgf8 embryos depleted of RA signaling (H) do not show an increase in otic cells but rather resemble non-transgenic RA-depleted siblings (G). Dorsal views with anterior towards the top. Scale bar: 35 µm.