(A) Mice were given a lethal dose of anesthetic at the indicated times, and contact radiographs of the distal femora were obtained on a Faxitron MX20 equipped with an FPX-2 Imaging system. Representative radiographs of the distal femur of Sam68+/+ (+/+) and Sam68−/− (−/−) mice revealed comparable radiopacity at 4 months (left). At 12 months (right), cortical thinning (arrow) and radiolucency (asterisk) were apparent in the distal femur of +/+ mice but not −/− mice.