Species Differences in the Reaction of the Mammalian Skeleton to Estrogens.

Abstract

Estrogenic steroid hormones stimulate endosteal bone formation and inhibit bone resorption in mice; this effect is similar to, but not identical with, the effect in birds. In young growing rats, the same substances do not lead to the production of endosteal bone, but the appearance of excessive bone formation is simulated by an inhibition of resorption of spongy bone. The histological picture in rats is differentiated from that in mice by the fact that in rats the unresorbed spongiosa retains its cores of cartilage matrix, thus demonstrating its endochondral, rather than endosteal origin. In other rodents, such as hamsters, guinea pigs, and rabbits, and also in cats and dogs, estrogens exhibit no specific effects on bone formation, but produce a non-specific retardation of the growth of bone.