Body weight varies with gender and age but not with genotype. Comparison of male (M) and female (F) DBL and TTA transgenic animals at each time point used for imaging indicates no effect of genotype on overall body weight. Each data point represents a single animal; lines show mean ± SEM. Animals used for weight analysis were distinct from those used for imaging but were derived from the same congenic colony and reared under the same postnatal doxycycline regimen. No significant differences in mean weight were found between genotypes matched for gender and age (n=15, 13, 9, 18, 14, 14, 7, 15, per group as shown on graph, Student’s t-test). One comparison (M, 7 wk) approached significance (p=0.0653, ci −2.218 to 0.07365), however, this difference was not apparent 9 weeks later (p=0.6849, ci −1.53 to 2.282).