Previous maternal chemotherapy by cyclophosphamide (Cp) causes numerical chromosome abnormalities in preimplantation mouse embryos

This study investigated the consequences of maternal cyclophosphamide treatment on fertilization rate, development and chromosomal integrity of embryos. It also evaluated efficiency of two methods of classic and metaphase induction for chromosomes assessment. Two different groups of NMRI mice 2–3 weeks and 6–7 weeks were injected intraperitonealy with 75 mg cyclophosphamide/kg. Six weeks later, oocytes were recovered, fertilized and incubated for 3 days in 5% CO₂ in air. Eight to 10 cell stage embryos were subjected to chromosomal study. Cyclophosphamide in both experimental groups reduced the oocyte fertilization rate and in the 6–7 weeks group it was significantly lower compared with control group (P < 0.01). Also there was a reduction in 8-cell stage embryos formation from 48 to 72 h post-fertilization in both treated groups (P < 0.05). Aneuploidy increased in the treatment groups compared with controls, which in the older group was significant (P < 0.001). The success rate of the classic method to analyze metaphase plates was 30.1% and the success rate of heterokaryons formation with analyzable chromosomes was 67.8% in the metaphase induction method. In regards to the adverse effects of cyclophosphamide on fertilization rate, embryo development and chromosomal integrity of the mouse embryos, using Preimplantation Genetic Diagnosis in addition to Assisted Reproductive Technique is suggested.