Changes in the orientation of collagen fibers on the superficial layer of the mouse tibial bone after denervation: scanning electron microscopic observations.

This study was undertaken to evaluate the relationship between the mechanical stress loaded onto the bone and the orientation of collagen fibers formed by osteoblasts. The femoral, obturator, and sciatic nerves in the left posterior legs of 7-week-old mice were exposed and electroscissored to reduce the mechanical stress loaded onto the leg. Four weeks after operation, the tibial bones in the control and denervated legs were removed and observed by scanning electron microscopy (SEM) after NaOCl treatment. In the control right tibia, collagen fibers on the superficial bone matrix tended to be arranged parallel to the longitudinal axis of the bone. However, the arrangement of collagen fibers in the left tibia, which were immobilized for 4 weeks by denervation, was disorganized and ran in random directions. The findings suggest that the direction of collagen fibers in the bone changes in response to the mechanical stress loaded onto the bone, probably due to changes in the activity of osteoblasts in the denervated leg.