Steroidogenic capabilities of the early mouse embryo

Preimplantation embryos from ICR albino mice were used to determine progesterone and estradiol-17beta production during incubation in BMOC-2. Following culture of 40 embryos/culture at either the morula, early blastocyst or late blastocyst stages, progesterone and estradiol-17beta contents were 192 +/- 27 and 82 +/- 22 pg, 289 +/- 50 and 147 +/- 46 pg and 157 +/- 28 and 88 +/- 23 pg, respectively, for incubated samples and 306 +/- 68 and 89 +/- 40 pg, 404 +/- 63 and 125 +/- 44 pg, and 241 +/- 54 and 86 +/- 39 pg, respectively for control samples. Although, there were significant stage of development and treatments effects (p less than 0.05) for progesterone, production of this steroid was not evident. These data suggest that the early preimplantation mouse embryo does not produce progesterone or estradiol-17beta in a defined culture system.