Effects of retinoic acid on pre-implantation embryo development in mice

In a previous study we had investigated the effect of in utero retinoic acid (RA) exposure on early post-implantation development at the blastocyst stage before implantation and immediately after implantation to understand the possible roles of RA in embryogenesis. The results showed that excess RA affected early post-implantation embryogenesis adversely. We designed the present study to investigate the effect of in utero RA exposure on pre-implantation embryos.

In the prospective animal study, pregnant female mice received early pre-implantation peanut oil with 50 mg/kg t-RA or 100 mg/kg t-RA by oral gavage on the morning of day 1 and 2 or late pre-implantation exposure on the night of day 2 and morning of day 3 of gestation. Mice were sacrificed late in day 3. The number and morphology embryos were recorded.

All mice given oral RA were sacrificed on the same day. The mean number of embryos per mouse and the percentage of different embryo stages in the t-RA treated mice administered at early pre-implantation embryo or late pre-implantation embryo stage were not significantly different from the controls. The mean number of embryos per 50 mg/kg mouse and the percentage of expanded blastocysts or early blastocysts/morulas did not differ from controls. In addition, the percentage of expanded blastocysts or early blastocysts/morulas was also not significantly different from the control group in 100 mg/kg late pre-implantation mice.

Mouse embryo development may not experience dose related adverse effects from non-physiological RA exposure during pre-implantation.