EFFECTS OF OESTROGEN PRIMING ON THE UPTAKE, METABOLISM AND BIOLOGICAL ACTIVITY OF PROGESTINS IN THE MOUSE UTERUS

Abstract

SUMMARY The effects of single subcutaneous injections of progesterone on uterine stromal and uterine epithelial mitosis and morphology varied non-linearly during the 6 days after oestrogen priming. Retention of locally applied progesterone was significantly less and recovery of its metabolites greater on day 1 after oestrogen priming than on day 6. Recovery of metabolites of two potent synthetic progestins, megestrol acetate and medroxyprogesterone acetate, was negligible after injection on either day. Retention of these progestins was the same whether given on day 1 or day 6, and was similar to the retention of progesterone when injected on day 6.