Fig. 7.

IHC. The protein expression of Runx2 is shown. A1 and A2 Longitudinal sections through the metaphysis. Runx2 is located in the preosteoblasts as well as osteoblasts of the inner layer of the periosteum (green asterisks). In addition, protein expression is noted in the hypertrophic chondrocytes (Hz, green arrowheads) of the growth plate and the osteoblasts of the POC (poc). B1–C2 Longitudinal sections through the developing epiphysis show the cartilage canals (cc), the marrow cavity (mc) and the SOC (soc). B1 and B2 At P 6 no difference in Runx2 expression is observed. Runx2 positive cells are seen in the lumen of the cartilage canals (cc), and, furthermore, several chondrocytes stained positively. C1 and C2 At P 8, Runx2 expression is encountered in several preosteoblasts within the marrow cavity (mc) of Wt controls. In the knockouts the SOC (soc) is already formed and numerous osteoblasts are Runx2 positive. The sections have the same magnification and are counterstained with hematoxylin; bar = 20 μm.