The use of C57Bl/6 × CBA F1 hybrid cross as a model for human age-related oocyte aneuploidy

Oocyte numbers decrease whereas the incidence of aneuploidy increases as women age. The molecular mechanisms underpinning this age-related decline in oocyte quality are not completely understood. Human oocytes are particularly error prone, with reports of aneuploidy rates as high as 50-60% (Fragouli et al., 2011; Kuliev et al., 2011). Mouse oocytes, in contrast, are generally more resilient to age-related aneuploidy, with different stains harboring disparate susceptibilities to chromosome segregation errors. This is clearly observed with aneuploidy rates as low as 9% (C57Bl/6 mice, 17-19 months) to 25% (B6D2F1/J mice, 16-19 months), but may be as high as 33% (MF1 mice, 15-17 months) to 43% (CD1 mice, 19-25 months) (Chiang et al., 2010; Sebestova et al., 2012; Shomper et al., 2014; Yun et al., 2014). Such variability in murine aneuploidy rates has hampered investigations into the causes of aged-related aneuploidy, with even the highest aneuploidy rates failing to reach those presented in older women.