[The role of osteoclasts in maintaining calcium homeostasis in newts]

The intensity of osteoclastic resorption and calcium contact were investigated in intact limb bones of the newts flown onboard of biosatellite Cosmos-2229 after amputation of their forelimbs and tail. X-ray microanalysis has shown an increase of calcium content in the bones on the 20th day after operation. Histological study revealed activated osteoclastic resorption on the inner surface of long bones. The newts exposed to weightlessness after the operation had the same level of bone mineralization as the operated ground control ones, but the number of polynuclear osteoclasts increased to a lesser extent.