Development and sister chromatid exchange of mouse morulae and blastocysts cultured in rat serum containing active metabolites of cyclophosphamide.

To establish an in vitro test system in which sera from animals treated with various chemicals can be tested for embryotoxic effects during the preimplantation period, mouse morulae and blastocysts were cultured in the presence of rat serum (RS) from animals which had been treated with cyclophosphamide (CPA). Development during in vitro culture for 96 h, cell number, chromosomal aberrations and sister chromatid exchange (SCE) were the end-points tested in exposed embryos. SCE frequency was the most sensitive parameter, indicating embryotoxic effects in preimplantation mouse embryos after only 1 h of exposure to RS-CPA.