Age-Related Changes of Cancellous and Cortical Bone Histomorphometry in Female Sprague-Dawley Rats

摘要

Double fluorescent labeled virgin female Sprague-Dawley rates were serial sacrificed between 3 and 16 months of age to characterize age-related skeletal changes. Histomorphometric analyses were performed on microradiographs and 20 millimeter undecalcified longitudinal sections of the proximal tibia and fourth lumbar vertebral body and cross sections of tibial shafts. The most consistent age-related changes among all test bone sites is a decrease in skeletal cellular based metabolic activities, including reductions in both recruitment and functional activity for osteoclasts and osteoblasts. Age-related cancellous bone loss with a discontinued trabecular structure was observed in proximal tibial metaphysis. Although cancellous bone mass in the lumbar vertebral body does not change with increasing age, there was a significant increase in tra ecular width. Age-related cortical bone change involves a redistribution of equal amounts of bone mass from the cortical-endosteal region to the subperiosteal region, leading to an expansion in both subperiosteal and marrow areas while cortical areas remain unchanged.