Abstract
Summary The effect of estrogen on rate of collagen synthesis and new bone formation in the mouse was investigated by high resolution autoradiographic methods. H3-proline and H3-glycine were administered on the first and seventh days, respectively, following estrogen treatment, and the mice were sacrificed at various intervals during the 24 hours following each tracer injection. The position of the radioproline label on metaphyseal tra-beculae indicated that the control bones grew in length 135 μ/day, whereas the bones from mice injected with estrogen 24 hours previously grew only 66 μ/day. Grain counts indicated that (a) uptake of the labeled amino acids by osteoblasts, and (b) subsequent transfer of the label with time after injection to surfaces of newly forming metaphyseal and endosteal bone were not affected by prior estrogen treatment. Silver grains were observed over the bone 16-24 hours after tracer administration. It was concluded that estrogen stimulates the processes which promote the differentiation of osteoblasts in the bones of mice, and that the hormone has no effect on the functional capacity of individual osteoblasts to synthesize and form collagen.