Histology of bone marrow of Csf1^op/Csf1^opmice expressing varying amounts of TgSPP and TgSGP. Low-power photomicrographs (× 25) above high-power photomicrographs (× 400) (boxed areas in low-power images) of midsagittal 5-μm sections of the distal femoral metaphyses of (A) 1-week-old mice stained for TRAP and counterstained with hematoxylin and (B) 2-month-old mice (top panels stained with H&E; bottom panels, serial sections stained for TRAP and counterstained with hematoxylin). ^* Osteoclasts; TR, trabecular region; and EP, epiphyseal plate.