Radiography was performed using a high-resolution soft X-ray system (SOFTEX, Ebina, Japan). Microcomputed tomography (μCT) scanning was performed using a ScanXmate-L090 scanner (Comscan Techno, Yokohama, Japan). Three-dimensional (3D) microstructural image data were reconstructed, and structural indices were calculated, using TRI/3D-BON and TRI/3D-BON-C software (RATOC Systems, Osaka, Japan). Bone histomorphometric analyses involving double calcein labeling were performed as described previously (39). Symbols and abbreviations used for histomorphometric parameters were as follows (40): ES, eroded surface; BS, bone surface; Oc.N, osteoclast number; Oc.S, osteoclast surface; O.Th, osteoid thickness; Ob.S, osteoblast surface; BFR, bone formation rate; MS, mineralizing surface. BFR/BS was calculated as MAR (mineral apposition rate) × MS/BS.