Figure 3.

Primary cilia of progenitor cells mediate mechanically induced bone formation. A) Transverse sections with fluorochrome labels marking new bone formation (green, calcein; red, alizarin). Bone formation measures were increased in loaded vs. nonloaded ulnae of control and experimental animals with primary cilia disrupted in bone marrow cells. B–D) Active mineralizing surface (MS/BS) (B), average interlabel width MAR (C), and BFR/BS (D). E–G) Relative measures (r) were obtained by subtracting nonloaded from loaded values: rMS/BS (E), rMAR (F), rBFR/BS (G). Disruption of primary cilia resulted in a diminished response to mechanical loading.