Body morphology of wild-type (WT) (mstn+/+) and Jekyll (mstn−/−) mice. A and B, Body weights and tibia lengths from mice of the indicated chase period/age; M, month. C–F, Mass of gastrocnemius and tibialis anterior (TA) muscles and of inguinal WAT and BAT. In all panels, significant differences between WT and Jekyll mice of given chase/age groups are indicated by asterisks (mean ± SEM, P ≤ .05, n = 6/group).