Figure 3.

Strain-dependent differences in Radium-223 uptake and bone microarchitecture. A) The distribution of the radionuclide was compared in age- and sex-matched C57Bl/6 and CD-1 (n = 5) as percent injected activity %IA ± SD. B) The greater overall uptake in the smaller long bones of the C57Bl/6 strain (insert) is enhanced when normalized to tissue mass (%IA/g ± SD). C) Regions of cortical and trabecular compartments for analysis by µCT. Three-dimensional bone volume from representative samples of (D) the trabecular (at two perspectives) and (F) cortical regions of the femur (scale bars = 500 µm). E) Quantitative µCT analysis of the distal femur reveals the larger tissue and bone volume of the CD-1 mice. The bone density bone volume fraction (BV/TV ± standard error of the mean) and other morphologic parameters of the trabeculae do not meet statistical significance; therefore, there is incontrovertibly greater bone area in the CD-1 mice. G) Likewise, analysis of the cortical bone establishes the greater size of the CD-1 (tissue and bone area ± SD) to that of C57Bl/6, despite the two strains having similar cortical area fraction values (bone/tissue area ± SD). Statistical significance was determined using an unpaired two-tailed Student’s t test; *P < .05.