Effects of increased earth gravity and estrone treatment on intact and healing avian radii.

Estrone, 0.4 mg administered daily for 7 days to developing chicks at 2 weeks post hatching, increased total mass and accelerated the rate of growth of the diaphyseal and proximal epiphyseal diameters of intact radii. Fractured radii of animals subjected to the same hormonal treatment displayed decreased bone weight but increased rate of growth of the proximal epiphyseal diameters and longer but thinner and lighter calluses. Two-week-old chicks, which had received no estrone, when exposed to a week-long 2g environment showed decreased intact bone weight and, with the exception of length of fracture callus, a reduction of all measured parameters of fractured bones. Estrone treatments of 0.4 mg administered daily to hypergravity-exposed animals over a week-long period resulted in greater length of fracture callus and increased rate of growth of the proximal epiphyseal diameter of both intact and fractured bones. The same treatments decreased weight and linear growth of fractured bones and width and weight of the fracture callus.