The Effect of Estrogen on Cartilage and Bone in Castrate C3H Mice †

The contrasting effects of estrogen upon the pubic symphysis and long bones in mice is well known.'0 `` "' At the time new bone was forming in the long bones the number of reticular fibers increased in the marrow.' Because observations were made only after 30 days following implantation of estrone, it was not possible to determine whether these fibers were associated with the formation of new trabeculae of bone or were remnants of trabeculae that were undergoing resorption and reconstitution. Glycogen, alkaline phosphatase, and calcium salts were demonstrated in the reticular stroma of newly forming membranous bone in pig embryos.' Therefore, it seemed profitable to study the distribution of these substances as well as reticular fibers in the long bones after short periods of estrogen treatment in order to determine whether or not an analogous process occurs in the development of endosteal bone in response to estrogen. Considerable data are available on the chemical composition and histochemical properties of the guinea pig symphysis during pregnancy and after treatment with estrogen and relaxin.4"1 1 2 f " " ' The mouse symphysis has been studied histochemically only with toluidine blue and PAS during pregnancy,' and with toluidine blue alone in castrate mice receiving hormonal treatment.' In the present experiment, the knees and the pubic symphyses of castrate mice were examined with the use of histochemical methods at daily intervals during a 30-day period of estrogen treatment in order to trace and compare the changes in response to estrogen at these two sites.