Fig. 6. Hypomorphic Fgf10 mutants phenocopy the mammary defect of Gli3^Xt-J/Xt-J embryos. Boxed areas in A,B,E,F are shown at high magnification in C,D,G,H. (A-D) Whole-mount in situ hybridization for Wnt10b reveals the absence of placode 3 in an E11.25 (43 somite) Fgf10 hypomorphic (Fgf10^mlcv/-) mutant. (E-H) Whole-mount in situ hybridization for Lef1 reveals the absence of bud 3 in an E12.5 Fgf10 hypomorphic mutant. (I,J) Hematoxylin/Eosin-stained sections, showing the absence of the stratum intermedium in an E11.5 (45 somite) mutant. Arrows in D and F indicate morphological limb defects in Fgf10 hypomorphic mutants, while limbs are totally absent in Fgf10^-/- embryos. Abbreviations: sg, stratum germinativum; p, periderm; s, somite stage. Scale bars: 10 µm in M,N; 100 µm in C,D,G,H; 1 mm in A,B,E,F.