Fig. 5. Ectopic FGF treatments induce Bmp2 and Bmp7 expression in the canal pouch. Expression of each gene is indicated on the left of each panel; treatment group is indicated on the right. Expression is shown 24 hours after FGF2 bead implantations at E3 (B,D) and E4 (F,H,N), 3 days after RCAS-Fgf3 infection at E4 (J), or 24 hours after FGF10-heparin bead implantations at E3 (L). (A-D,K,L) Double arrows indicate differences in Bmp gene expression in the dorsal canal pouch (presumptive common crus domain) between treated and control specimens viewed in wholemounts. (E-H) The approximate level of each section is indicated in either A or B. (E-J) Arrows indicate Bmp2 expression normally evident in the rim of the prospective canal pouch; arrowheads indicate differences between experiments and controls in Bmp2 expression and epithelial thickness in the central part of the canal pouch. (M,N) Soho1 expression persists in the central region of the canal pouch (arrowhead) in both control and treated ears. Orientations in A applies to B-D,K,L; E applies to E-J,M,N. White arrows in B and L indicate the implanted beads. Scale bars: in E, 100 µm for E,F; in G, 100 µm for G,H; in J, 50 µm for I,J; in N, 50 µm for M,N.