Fig. 4. Gli3^–/– limbs are delayed in endochondral ossification. Serial sections of E16.5 wild-type (A,C,E,) and Gli3^–/– (B,D,F) limbs were hybridized with riboprobes as indicated. (A-D) Expression of Ihh and Col10a1 reveals normal regions of prehypertrophic and hypertrophic chondrocytes. (A,B) The overall size of the radius in wild-type mice (light-green bar) is reduced in Gli3^–/– mutants (dark-green bar, P=0.0036), and the ossification is slightly delayed (compare dark- and light-blue double-headed arrows in wild-type and Gli3^–/– limbs, respectively). (E,F) The expression of Ptch is unchanged in Gli3^–/– limbs.