When undergoing IVF, it is essential to be able to preserve any additional embryos not used for transfer. This can be done by the cryopreservation of embryos using controlled-rate cryopreservation equipment or by applying newer vitrification techniques. These frozen embryos can then be stored for extended periods of time in liquid nitrogen at about -180 degrees centigrade until needed for a follow-up embryo transfer. Frisco IVF has some of the best live birth rates in the world when freezing and thawing blastocysts.