The effect of cyclophosphamide on rat blastocysts in vitro and their subsequent development following transfer to pseudopregnant rats

These investigations were undertaken to assess the effects of cyclophosphamide (CPA) on rat blastocysts. In the first set of experiments, blastocysts were exposed to 100 μg/ml CPA in culture for 48 h. In the second experiment, blastocysts were cultured for 48 h following injection of 20 or 40 mg/kg of CPA to pregnant rats on day 4 of gestation. In the third experiment, blastocysts were cultured for 2 h in the presence of 100 μg/ml of CPA and then transferred to pseudopregnant rats. The results from the first experiment revealed a clear toxic effect of CPA on blastocysts following culture. A similar effect occurred when blastocysts were harvested and cultured following in vivo injections of CPA. In the third experiment a clear embryotoxic effect (larger number of resorptions and retarded embryos in comparison to control) was found on day 13 of gestation. The origin of activation of CPA by the blastocysts could not be ascertained from the above results.