Cytogenetic characteristic of osteogenic cells in vitro as perspective predictors of osteopenia under microgravity.

Mechanical stimulation of bone tissue determined by earth gravity is one of the main factors mediating the nature, rate and direction of functional adaptation of the bone system in the process of onto- and phylogenesis. Theoretically expected losses of bone mass under condition of mechanical load deficit under microgravity (osteopenia, osteoporosis) may become a factor that limits the duration of space flights. As a result of long-term studies some properties and regularities of change in human tissue after prolonged space flights (for 5-7 months) were established.