Biology of Reproduction, Vol 16, 627-632, Copyright © 1977 by Society for the Study of Reproduction

The Effect of Estradiol on RNA Synthesis in Preimplantation Mouse Embryos Cultured in vitro

¹ Department of Biochemistry and Biophysics, Iowa State University, Ames, Iowa 50011

The effect of concentrations of 17--estradiol from 10^-5M to 10^-9M, on RNA synthesis in preimplantation mouse embryos cultured in vitro, was probed. It was found that blastocysts incubated with [³H] uridine and hormone simultaneously, from h to 24 h, showed no major stimulation or inhibition of RNA synthesis. In a second set of experiments the differential sensitivity of 8-cell and blastocyst embryos to estradiol was probed. It was found that preincubation with 10^-5 to 10^-9M estradiol for 21 h, followed by a three hour incubation with [³ H] uridine, also showed no major stimulation or inhibition of RNA synthesis in either 8-cell or blastocyst embryos. It is concluded that RNA synthesis in 8-cell and blastocyst mouse embryos is refractory to modulation by exogenously added estradiol. Several explanations are put forth to account for these results.

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ACKNOWLEDGMENTS We thank Ms. Ruth Graves for technical assistance. This work was supported by a grant from The Population Council, New York, and in part by NIH grant AI-11752.