Fig. 3. Fgf signaling alters the expression of early AP-specific genes. Dorsal views of whole embryos at late gastrula stage. One- to two-cell embryos were injected with mRNAs for fgf3 (B,F,J) or RNA encoding the dominant negative Fgf receptor, XFD (D,H,L). Embryos were stained either with cyp26 (A-D), hoxb1b (E-H) or otx2 (I-L). The anterior expression of cyp26 and otx2 was suppressed by Fgf3 (B,J) and expanded in a posterior direction by XFD (D,L). Expression of the posterior gene hoxb1b was expanded by Fgf3 (F) and suppressed by XFD (H, arrowhead). The entire embryo is affected by injection at the one-cell stage (B), while in some cases only half the embryo is affected when one of two cells is injected (H).