After 3 h of BrdU incorporation (1.6 mg/100μl), dividing cells were visualized in tibia sections from wt and nm (A, B, red) E6 embryos after IHH mRNA was detected by FISH (C, D, green). Sections were counterstained with DAPI. White lines indicate the areas enlarged in the merged images (E, F). Numbers of BrdU-positive cells were quantified in ten comparable but independent areas from both wt and nm embryos (G). Data was evaluated for statistical significance using the Student's t-test. *<0.008