INHIBITION OF PELVIC CHANGES OCCURRING DURING PREGNANCY IN MICE BY TESTOSTERONE PROPIONATE1

Abstract

DURING LATE PREGNANCY the pelvis of the guinea pig enlarges by a hyperI trophy of an interpubic ligament. These changes have been reproduced experimentally in female or male guinea pigs following adequate treatment with estrogens and relaxin (1). They involved a transformation of the interpubic synchondrosis to a pubic symphysis and then, associated with some bone destruction, a proliferation of the fibrous ligament to separate the pubes for variable distances (2,3). A sexual dimorphism of the pelvis also exists in the pocket gopher, first becom ing apparent at sexual maturity. The pubic bones were decalcified at the symphysis under the influence of the ovarian hormone (4). A pelvic sexual dimorphism also occurs in another rodent, the mouse (5). The pubic bones separated at the symphysis during the first pregnancy and these changes were augmented with succeeding pregnancies. The alterations of pelvic structure were reproduced and augmented by the injections of estrogens.