Fig. 7. FRL-1MO inhibits an early step in the neural induction of Xenopus embryos. Albino embryos were injected with 20 ng of FRL-1MO (B,D,F,H), or FRL-1-4misMO (A,C,E,G) and 250 pg of lacZ into the dorsal marginal zone of a blastomere at the 4-cell-stage for analysis of chordin and a dorso-animal blastomere of 8-cell-stage embryos for analysis of zic3, soxD and Xngnr-1. They were cultured until stage 10.5 for whole-mount in situ analysis of chordin (A,B) and until stage 13 for analysis of zic3 (C,D), soxD (E,F) and Xngnr-1 (G,H) and then stained in the MO-injected region with red gal. The suppression of the neural markers zic3 (D, 77%, n=22), soxD (F, 84%, n=37) and Xngnr-1 (H, 86%, n=21) was observed in the FRL-1MO-injected region whereas chordin was not suppressed (B, 0%, n=29). However, there was no change in the FRL-1-4misMO-injected region (A, 100%, n=22; C, 96%, n=26; E, 93%, n=75; G, 91%, n=48). Arrows in G and H indicate trigeminal ganglia, where the expression of Xngnr-1 was suppressed in H.