It has been shown that estrogens cause definite gross anatomic alterations in the joints of the pelvic ring in the guinea pig.1 Hisaw2 has demonstrated experimental relaxation of the pubic symphysis with the relaxative hormone of the corpus luteum. Little attention, however, has been paid to the minute histologic changes occurring at the pubic symphysis during the transformation. Furthermore, similar correlative histologic studies of other bones and joints of guinea pigs are lacking.3
In the light of these facts it seemed of interest to investigate the effects of subcutaneous injections of estrogen4 in mature castrated guinea pigs on (1) the tissues of the pubic symphysis and the sacroiliac joints in situ, (2) autogenous transplanted segments of the pubic symphysis with attached ligaments, and (3) the capsular tissues of the major joints.
Twelve male guinea pigs, each weighing approximately 400 Gm., were castrated under general anesthesia.