Fig. 4.

Immunohistochemical staining of fatigued specimen and ELISA for osteocalcin and osteopontin quantification. (A) Associations of dilatational bands (Upper) and diffuse damage (Lower) with osteocalcin, osteopontin, and phosphoproteins. As seen in the micrographs, osteocalcin, osteopontin, and phosphorylated proteins colocalize with the bands (highlighted red by basic fuchsin, which stains for damage), indicating their possible role in band formation. (B) Mouse bones lacking OC (OC^−/−), OPN (OPN^−/−), and OC-OPN (OC-OPN^{−/−;−/−}) showed a significantly lower level of fracture toughness than their WT controls but were not different from each other. (C) Mouse bones lacking OC (OC^−/−), OPN (OPN^−/−), and OC-OPN (OC-OPN^{−/−;−/−}) showed a dramatic reduction in diffuse damage compared with their WT controls but were not different from each other. *P < 0.05; ***P < 0.001.