Abstract
The effects of pituitary growth hormone on the development of 9-day chick embryo femora were studied in tissue culture. Pair-mate bones were cultivated by the roller-tube culture method without plasma, in which one of each pair was grown in the medium consisting of chick embryo extract, horse serum and saline solution and another in the plus-growth hormone medium.
In a high concentration, 100μg/ml, the radiosulfate uptake of the bones was markedly retarded and both elongation and dry weight of the treated bones were considerably less than those of the control. With decreasing concentration, however, the reduced uptake of 35S-sulfate and the inhibited longitudinal growth were restored. And in a low concentration, 6.25μg/ml, the incorporation of labeled sulfate into the treated bones significantly increased over that of the control and a significant enhancement was found also in the elongation, And, from a consideration that a concentration of 6.25μg growth hormone per ml of the medium would be regarded as within the physiologic level of concentration, it was suggested that growth hormone acts directly on the development of skeletal tissues in living organisms. As to the dry weight of the bones, however, a slight decrease was observed in all the concentrations used.
