Fig. 6.

Involvement of Ier2 and Fibp1 in forerunner cell formation and in charon expression in Kupffer's vesicle. (A–H), embryos were fixed at the 5-somite stage. Expression patterns of fgf8 (A and D), ier2 (B–D), and cha (C) in normal embryos. Red arrowheads indicate Kupffer's vesicle. (A and B) In situ hybridization with purple staining. (C and D) Fluorescence in situ hybridization. (E–H) Charon expression depends on FGF signaling and Ier2/Fibp1 function. Embryos were hybridized with cha probe after injection of control MO (E), fgf8 MO (F), ier2 MO plus fibp1 MO (G), and fgf8 MO + ier2 RNA + fibp1 RNA (H). (I–L) Embryos at 80% epiboly hybridized with casanova (cas) probe, which highlights dorsal forerunner cells labels endoderm. An asterisk points to dorsal forerunner cells. The embryos were injected with the MO indicated. For levels of MOs see legends to Fig. 4 and 5. n, notochord.