Delayed Wnt Fgf signaling dynamics in stalled primordia. (A) In control embryos, the primordium (pLLp) migrates and separates from the pLL ganglion (pLLg) by 22 hpf and lef1 expression is restricted to the leading domain. (B,C) With migration inhibited in cxcl12a morphants and PP1-treated embryos, the primordium remains juxtaposed with the pLLg and lef1 expression remains broad. (D) pea3 expression at the trailing end of the primordium in controls at 22 hpf. (E,F) The pea3 expression domain is still at the trailing end of the prospective primordium in the absence of migration; however, the pea3 domain is in the middle of a broad lef1-expressing domain, which now represents the juxtaposed primordium and the pLLg. (G-I) snail1b expression in control, cxcl12a morphant and PP1-treated primordia at 22 hpf. OV, otic vesicle. n=25 for each of two independent experiments. Dotted lines encircle pLL primordia.