Abstract
Ultrastructural changes of chondrocyte mitochondria in strontiuminduced rachitic tibia epiphysis were revealed by transmission and scanning electron microscope. After per os administration of a strontium diet for 2 weeks, the following rachitic changes occurred in the tibial epiphyseal growth plates: The growth plates in the rats fed the strontium diet (strontium group), in particular, the hypertrophic zone, became thicker than those fed the control diet. X-ray microanalysis of the deep hypertrophic zone in the strontium group revealed the presence of abundant cations such as calcium, phosphorus and strontium, probably indicating interference with progressive ordinary mineralization. The hypertrophic chondrocytes in the strontium group had many longitudinally elongated, bent or bifurcated mitochondria. The mineralization disturbance and arrest of terminal differentiation of chondrocyte by the rachitic condition may be responsible for the morphological alteration of the chondrocyte mitochondria. These findings indicate that chondrocyte mitochondria correlate with their surrounding mineral phase and are ultrastructuarlly affected by disturbance of the correlation.
