Fig. 3.

Mineralization and load-induced bone formation are severely attenuated in mice lacking OCPs. Skeletally mature Rosa26^DTA control and Prx1CreER-GFP;Rosa26^DTA ablation animals injected with tamoxifen were exposed to ulnar loading and the resulting mineralizing surfaces were labeled with calcein (green) and alizarin (red) fluorochrome dyes. Mice lacking periosteal OCPs demonstrated poor mineralization, indicated by a lack of labeling at the periosteal surface in both loaded and nonloaded ulnae (a). We performed dynamic histomorphometry and confirmed this visual observation (b). Ablated animals also exhibited an inferior mineral apposition rate (c), resulting in attenuated bone formation compared with controls (d). Loaded ulnae were normalized to nonloaded contralateral limbs. Micrographs were collected at 10X. Data are reported as mean and standard error. n = 16 for each group, ***p < 0.0001. rBFR/BS relative bone formation rate/bone surface, rMAR relative mineral apposition rate, rMS/BS relative mineralizing surface/bone surface