Skeletal responses to spaceflight

The effect of gravity on the skeletal development and on the bone composition and its regulation in vertebrates is discussed. Results are presented from spaceflight and ground studies in both man and rat on the effect of microgravity on the bone-mineral metabolism (in both species) and on bone maturation and growth (in rats). Special attention is given to a ground-based flight-simulation rat model developed at NASA's Ames Research Center for studies of bone structure at the molecular, organ, and whole-body levels and to comparisons of estimated results with spaceflight data.