Peculiarity of Ultrastructure and 45Ca Methabolism of Osteoclasts in Conditions of Hind Limb Unloading and Microgravity
Using methods of electron microscopy, morphometry and cytochemistry the peculiarities of ultrastructure of osteoclasts and resorptive processes of the mineralized matrix in spongy bone of the rat femoral bone metaphyses following the experimental hind limb unloading model (28 days), as well as in rats exposed on American Space Station SLS—2 (2 weeks) were studied. The methods of light and electron microscopy radioautography 45Ca were used in the experiment of hind limbs unloading. The results of investigations demonstrated that in zones of adaptive remodeling the resorption and destruction processes in the bone tissue increase under the supportive unloading. It takes place by increasing of functional activity of osteoclasts (in microgravity conditions we registered the «giant» osteoclasts). The dynamics of 45Ca —incorporation into osteoclasts is an indicator of a direct involvement of cells in calcium transfer from the resorpting mineralized matrix to intercellular environment and intensification of this process at hind limb unloading model.