Fig. 5. Whole-mount in situ hybridization for Shh and Fgf10 in embryonic Fgf9^-/- lungs. (A,B) In situ hybridization for Shh in E14.5 control (A) and Fgf9^-/- (B) lungs. Epithelial Shh expression in Fgf9^-/- lung is comparable with that in control lungs. (C-F) Fgf10 expression in E12.5 control (C,E) and Fgf9^-/- (D,F) lungs. (E,F) Higher magnification images of the boxed regions in C,D, respectively. Note comparable expression of Fgf10 in mesenchyme distal to airway buds in control (C,E) and Fgf9^-/- (D,F) lungs. (G-J) Fgf10 expression in E14.5 control (G,I) and Fgf9^-/- (H,J) lungs. Fgf9^-/- lung (H) shows reduced expression of Fgf10 relative to control lung (G). Note the absence of Fgf10 expression in the region of H indicated by the arrow and the presence of Fgf10 expression in the corresponding region of G. The indicated Fgf10 negative buds (arrow in H) are dilated with little surrounding mesenchyme (similar to buds in Fig. 2J); this suggests that absence of Fgf10 expression may be due to a lack of mesenchymal tissue. (H is shown at 1.4x the magnification of G.) (I,J) Higher magnification images of the boxed regions of G,H, respectively. Note control Fgf10 expression in the mesenchyme between epithelial buds (arrowheads in I). No Fgf10 expression is seen in the comparable regions of the Fgf9^-/- lung (arrowheads in J). (I,J are at the same magnification.)