Fig. 5. Rostrally expanded expression of Irx1 in Fez^-/-Fezl^-/- embryos. Irx1 and Six3 expression in control (A,C,E,G,I) and Fez^-/-Fezl^-/- (B,D,F,H,J) embryos at E10.0 (A,B), E9.5 (C,D,I,J), E9.0 (E,F) and E8.5 (G,H). Lateral views, with anterior to the right. Irx1 expression was not significantly different between Fez^-/-Fezl^-/- and control embryos at E8.5. A rostral expansion of Irx1 expression was detected at E9.0 in Fez^-/-Fezl^-/- embryos (arrow). At E9.5 and E10.5, the rostral limit of Irx1 expression (arrows) reached the caudal edge of the telencephalon (marked by dots). Expression of Six3 was not significantly affected in Fez^-/-Fezl^-/- embryos at E8.5 (data not shown) and at E9.5 (I,J).