Age changes on bone size and mass in two strains of senescent rats

6-month-old Buffalo and Fisher inbred rats were compared with their respective senescent counterparts. It appeared that length as well as weight of the various sections of the skeleton increased into old age. However, in some skeletal parts, length increase was greater than weight increase, so that relative robusticity of those parts, relating weight to length, dropped. The two different strains of rats showed differences in age-related bone reactions. Thus, while in humans, age-related bone loss is absolute, in rodents it is relative in certain sections of the body, or does not occur at all, but strain-dependent differences in rats have some parallels in human breeding populations.