Analysis of osteoclastogenesis after osteoblast depletion. Bone marrow suspensions were plated in media containing 30 ng/mL M-CSF plus 30 ng/mL RANKL. Five days later, cells were fixed and stained for tartrate-resistant acid phosphatase (TRAP). Osteoclast generation was evaluated by counting the number of TRAP-positive multinucleated cells. The groups considered are the following: Col2.3ΔTK mice treated with PBS (□) and Col2.3ΔTK mice treated with GCV (▦). The left graph shows the data from groups treated for 14 days (2 experiments); the right graph, data for mice treated for 25 days (1 experiment).