Osteoclast compartment staining in irradiated (TBI) and control mice. Photomicrographs of a bone (Bo) and BM section from the metaphysis stained with tartrate-resistant acid phosphatase (top; purple) and with anti–cathepsin K antibody (bottom; red), as 2 reliable osteoclast markers. Staining intensities did not differ appreciably between the 2 groups. Scale bar (top) represents 200 μm; scale bar (bottom) represents 100 μm.