Fig. 6. Osteogenic differentiation is abnormal in Icap-1^-/- calvaria. Frontal sections through the parietal bones and the sagittal suture of Icap-1^+/+ and Icap-1^-/- newborn mice stained for (A) AP, (B,C) osteonectin, (D,E) COL1, (F) FGFR1 and (G) FGFR3. C and E are 400x magnification views of the osteogenic front region in B and D, respectively. Dashed lines represent bone borders and osteogenic front area. B, bone; i.m., intersutural mesenchyme. Note the reduced expression of the osteogenic and differentiation markers in Icap-1^-/- tissue. (H,I) Whole-mount in situ hybridization on calvaria of E17.5 embryo was performed to detect either Runx2 (Cbfa1) (H) or Bsp (I) transcripts in Icap-1^+/+ and Icap-1^-/- embryos. The upper panel of each pair is an overview of the full calvaria; the lower panel is a closer view of the osteogenic front (boxed in the overview). Scale bars: 2 mm.