Influence of estrogen and progesterone on the incorporation of35S methionine by blastocysts in ovariectomized mice

摘要: Incorporation of 35S methionine by mouse blastocysts in vivo, as detected radioautography, provides a presumptive measure the blastocysts' protein synthesizing activity. Normally, there is marked increase incorporation between 95 and 99 hours post coitum. To determine whether or not ovarian hormones influence blastocysts, mice were ovariectomized on day 4 pregnancy injected with progesterone and/or estradiol 17-β given single injection methionine. The results demonstrate that incorporated vivo only after combined estrogen treatment; 12 to 14 are required for maximum response. Further, transferred (101–103 coitum) from intact donors ovariectomized, pseudopregnant recipients untreated treated estradiol. methionine, thus suggesting hormonally induced changes responsible initiating synthesis. These findings provide tentative explanation mechanism involved normal implantation terminating embryonic diapause delayed lactation.