Cross-Species Comparison of Chromosomal Instability During Mammalian Pre- Implantation Development

One of the first major milestones in early mammalian development is blastocyst formation and yet, less than half of pre-implantation embryos from most mammals will reach this stage following in vitro fertilization (IVF). A leading cause of IVF failure and embryo loss in humans is the presence of whole chromosomal imbalances, or aneuploidy. Although more likely to arrest at the cleavage-stage, aneuploid embryos may still form blastocysts and often morphologically indistinguishable from chromosomally normal (euploid) embryos. Chromosomal mis-segregation in oocytes during meiosis is considered the primary reason for aneuploidy in cases of advanced maternal age. However, mosaic aneuploidies, which are mitotically derived, occur just as frequently and irrespective of maternal age. The potential cause(s) of mitotic aneuploidy, whether it can be non-invasively detected, and if preimplantation embryos from other mammalian species are also chromosomally unstable was the focus of this study. Using a combination of time-lapse imaging to monitor embryo development ...