Figure 3  Radiologic Assessment of the Femur of Young and Old Sam68+/+ and Sam68−/− Mice
(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.
(B) Bones were dissected free of soft tissue and fixed overnight in 4% paraformaldehyde before scanning on a Skyscan 1072 static instrument equipped with 3D Creator analytical software. Representative three-dimensional re-constructions and two-dimensional cross-sectional scans demonstrated similar architecture in the distal femur of Sam68+/+ (+/+) and Sam68−/− (−/−) mice. In keeping with the results from Faxitron x-ray, trabecular bone (asterisk) and cortical thickness (arrow) were reduced in the femur of 12-month-old +/+ mice compared with all other groups. The images are representative of those from five to seven animals in each group.