Fig. 2. Gene expression changes in Ednra^–/– embryos. Whole-mount in situ hybridization analysis of gene expression in E10.5 wild-type (Ednra^+/+) and Ednra^–/– embryos using digoxigenin-labeled cRNA riboprobes. Embryos are shown in ventral view, with the heart and outflow tract removed to aid in visualization. (A,B) Wnt5a expression spreads into the distal half of the mandibular arch in Ednra^–/– embryos (black arrow in B). (C,D) Dlx1 expression spreads into the distal mandibular arch in Ednra^–/– embryos (C; compare broken yellow lines in C and D). (E,F) Msx1 expression appears to spread proximally in Ednra^–/– embryos (F; compare broken black lines in E and F). (G,H) Twist expression expands distally in Ednra^–/– embryos (H; compare broken yellow lines in G and H). (I,J) Dlx2 expression also spreads more distally in Ednra^–/– embryos (J; compare broken yellow line in I and J). This expansion is accompanied by loss of epithelial expression (compare arrows in insets). (K,L) Bmp4 expression is also downregulated on the rostral epithelium of Ednra^–/– embryos (L; compare arrows in insets in K and L). (M,N) Dlx5 expression is almost completely lost in the mandibular arch of Ednra^–/– embryos (N). (O,P) Dlx6 expression is also absent in the mandibular arch of Ednra^–/– embryos (P). (Q,R) Hand2 expression, which is observed in the distal two-thirds of wild-type embryos (Q), is almost completely absent in Ednra^–/– embryos, though some expression remains in the distal arch (R; arrow in inset). 1, mandibular region of first pharyngeal arch; 2, second pharyngeal arch.