Fig. 5.
Absence of bone marrow cells and reduced density of osteoclasts in the region of ectopic mineralized cartilage. (A) H&E staining showed that in the zone of mineralized cartilage (marked by the bracket) in the femur of 6-wk-old Osxpostnatal mutant, there are almost no bone marrow cells (red asterisks). The spaces between the mineralized cartilages are filled by capillaries (green asterisks). Bone marrow cells are found below the zone of mineralized cartilage in the mutant. (B) Histomorphometry analysis of osteoclasts (Oc) in metaphysis (excluding cortex) of femurs of tamoxifen-treated 2-mo-old control and Osxpostnatal mutants. BS represents mineralized tissue surface. Tb-1: the area measured from the growth plate to 500 μm distally; tb-2: the area measured from the end of tb-1 to 500 μm distally; tb-3: the area measured from the end of tb-2 to 700 μm distally. n = 3/genotype group. *P < 0.05, **P < 0.001. (C) TRAP staining showed that the size of osteoclasts found in the Osxpostnatal mutant was much smaller than the ones in the tamoxifen-treated control mice. Arrows indicate osteoclasts.