Histological images of fracture healing.

<p>(A) Alcian blue-stained sections. Scale bar = 500 μm. <i>DAP12</i>^{<i>–/–</i>} mice showed more residual cartilaginous tissue and delayed woven bone formation (arrow) at day 10. Substantially impaired cortical shell formation on the callus surface was observed in <i>DAP12</i>^{<i>–/–</i>} mice at day 14 (arrowhead). <i>DAP12</i>^{<i>–/–</i>} mice showed residual cartilage matrix in the peripheral callus, less original cortex absorption and delayed bone remodeling at day 28. (B) Quantitative histomorphometric analysis of the fractured callus in B6 and <i>DAP12</i>^{<i>–/–</i>} mice. There was no significant difference in callus volume between <i>DAP12</i>^{<i>–/–</i>} and B6 mice. Hematoma area was significantly larger in <i>DAP12</i>^{<i>–/–</i>} mice than in B6 mice at day 7. The newly formed bone area was significantly smaller in <i>DAP12</i>^{<i>–/–</i>} mice than in B6 mice at days 7 and 10. Cartilage area was significantly larger in <i>DAP12</i>^{<i>–/–</i>} mice than in B6 mice at day 10. *<i>p</i><0.05, **<i>p</i><0.01.