THE EFFECT OF VARIOUS COMBINATIONS OF PROGESTERONE AND OESTROGEN ON THE SYMPHYSIS PUBIS OF OVARIECTOMIZED MICE

Abstract

SUMMARY The effect of various combinations of oestrogen and progesterone, injected for periods of 23, 28 and 36 days, on the symphysis pubis of 127 ovariectomized, virgin mice is described. The work is an extension of earlier work in which other combinations of the same hormones were used. The results of both sets of experiments, present and past, show that, when injected into ovariectomized mice for periods at least as long as that of normal pregnancy, (1) 25, 100, 250, 1000 and 1500μg/day progesterone do not potentiate the action on the symphysis pubis of 1·5–25μg/day oestrogen, and that (2) these combinations of the two hormones do not produce changes in the pelvis similar to those which occur at the end of normal pregnancy, or (3) which can be produced in ovariectomized mice by injecting oestrogen and relaxin. The results confirm that there is apparently a species difference between the mouse and the guinea-pig in this respect.