Analysis of early bovine embryogenesis after in vitro and in vivo oocyte maturation by time-lapse imaging and 3-D confocal microscopy

In the in vitro production of embryos in humans and animals it is
aimed to produce embryos of good quality in order to reach a high
pregnancy rate after the transfer on a recipient. Nevertheless,
data until 2007 show that in Europe the pregnancy rate after the
transfer of human IVF embryos was only 33% (de Mouzon et al.,
2012). Recently time-lapse imaging of early embryonic cleavage was
found to be a helpful and non-invasive tool to predict the
developmental capacity of embryos and select embryos of good
quality (Wong et al., 2010, Sugimura et al., 2012). As the
morphokinetic parameters of the first and second cleavage were the
most predictive values, the fate of an embryo seems to be, at least
partly, already determined very early in embryogenesis. This
determination of the developmental competence might even go back
further namely until oocyte maturation. In this experiment we used
bovine embryos as an animal model to study the reasons for success
and failure of mitotic cleavage during early embryo development.
First a live monitoring system for the observation of bovine
embryos was applied in order to search for the values that are
highly predictable for the developmental competence to the
blastocyst stage. To consider the effect of the oocyte maturation
onto the further development, we observed embryos from oocytes
after in vitro (n=398) versus in vivo maturation (n=143). In
average embryos that developed to the blastocyst stage showed an
earlier timing of the first, second and third cleavage than embryos
that arrested (p