3.6. Histology and Micro-CT Analysis

Mouse knee joints were fixed with 4% paraformaldehyde for 48 h and then decalcified with 0.5 M ethylenediaminetetraacetic acid (EDTA, pH 8.0) for 2 weeks. Bone tissues were embedded in paraffin and sectioned (4 μm) using a rotary microtome. Tissue sections were stained with safranin O for assessment of the subchondral region and visualized by optical microscopy (Leica, Wetzlar, Germany). For micro-CT analysis, a paraformaldehyde-fixed femoral bone was scanned using the high-energy spiral scan micro-CT (Skyscan 1173; Bruker, Billerica, MA, USA). Two-dimensional CT images were reconstructed using the CTvox Software version 3.2 (Bruker).