Description
Despite great improvements in assisted reproductive technology (ARTs), the success of in vitro embryo production remains relatively low. Most of the oocytes used to produce in vitro embryos are recovered from smaller follicles, forming a heterogeneous population that must be matured in vitro. Since the original in vitro maturation (IVM ) experiments (Heilbrunn et al. , 1939) the process by which the most competent oocytes are selected to produce blastocysts remains similar and is still based on morphological aspects of the oocyte cytoplasm and the number of layers and compaction of cumulus cells attached to the oocyte surface (Armstrong, 2001, Coticchio et al. , 2004, Krisher, 2003, Lonergan et al. , 2003).