ABSTRACT
During preimplantation development in mammals, the epigenetic marks of the embryo are reseted within the female reproductive tract. Because epigenetic information is reversible and sensitive to environmental changes, reprograming take place under a finely controlled maternal environment. However, assisted reproductive technology implies the use of in vitro culture during this critical period, and in the majority of the occasions the composition of the media used is unknown. This, and the lack of basic knowledge about what is the actual in vivo environment, show the importance of improving media for mammalian embryo culture. It has been discovered that epigenetic changes on the embryo, which may modulate the neonatal birth weight, are probably associated with the composition of the culture media and incubating conditions. Thus, currently there are still questions under debate about what the optimal conditions and the duration of embryo culture as well as when to carry out the embryo transfer to the recipient (at cleavage or at blastocyst stage). Here we review the impact of embryo culture on epigenetics and the consequences for perinatal outcome.
