Embryo culture in vitro is critical for the success of embryo development. In the past, bovine fertilized oocytes were cultured in the serum free medium, such as SOF medium, for 40-44 h. The cleaved embryos then were transferred in a serum contained medium, 10% FBS SOF medium, and co-cultured with the cumulus monolayer for 5 days before being transferred into the recipients. This co-culture and serum culture system is believed to cause the large calf syndrome (LCS) in cattle.
Bovine embryo development by OPU-IVF
Renova Life Inc. (RLI) developed a modified SOF system, SAR IVC medium, which is completely free of serum and cumulus co-culture for embryos. Several embryonic promoting factors and small molecules are added into the medium, which the process significantly enhances the blastocyst development, and the compaction of inner cell mass cells (ICM) in the blastocysts. SAR IVC medium makes embryo culture simple and reliable for OPU-IVF operation; it may not require medium change during 7 d culture. Embryos are cultured at 39°C in humidified air and a mixed gas atmosphere consisting of 5% CO2, 5% O2 and 90% N2 for entire 7 d.