Fig. 4. FRL-1MOs specifically induced head defect phenotypes. FRL-1MOs were injected into animal blastomeres of 8-cell-stage embryos, which were grown to stage 40. (A) Uninjected embryo. (B) Embryo injected with 15 ng FRL-1MO showing defects of the head including lack of eyes. (C) Embryo injected with 15 ng of FRL-1-4misMO showing no defect. (D) Head structure defect induced by 15 ng of FRL-1MO was rescued by co-injection of 20 pg of FRL-15'UTR. (E,F) Some other EGF-CFC genes can rescue the head defect phenotype caused by FRL-1MO. (E) Co-injection with 20 pg of oep rescued head defects caused by microinjection of 15 ng of FRL-1MO. (F) Co-injection with 20 pg of mouse cripto also rescued head defects. (G,H) FRL-1MO-second suppressed neural formation as well as FRL-1MO. (G) Embryo injected with 40 ng of FRL-1MO-second showing the same phenotype as the FRL-1MO-injected embryo. (H) Head structure defects caused by microinjection of 40 ng of FRL-1MO-second was rescued by co-injection with 20 pg of FRL-15'UTR.