The effect of progesterone, estradiol and serum on RNA synthesis in preimplantation mouse embryos cultured in vitro.

Abstract

The effect of concentrations of progesterone, from i0�-lOM. on RNA synthesis in pre- implantation mouse embryos was tested. It was found that there was no major stimulation nor inhibition of RNA synthesis in 8-cell or blastocyst mouse embryos cultured in vitro in the presence of progesterone. The same absence of an effect was observed when progesterone and estradiol were administered together. These results complement an earlier study which showed that estra- diol alone does not affect RNA synthesis in preimplantation mouse embryos. Although preim- plantation mouse embryos are refractory to stimulation of RNA synthesis by estradiol and/or progesterone, RNA synthesis is markedly stimulated when the embryos are exposed to 15% mouse serum which was heated to 56#{176}C for 30 mm. The nature of this stimulatory factor is unknown. Nonheated mouse serum was found to inhibit RNA synthesis in 8-cell and 2-cell preimplantation mouse embryos.