Embryo vitrification
Day 7 and 8 excellent and good expanded blastocysts
were vitrified in fiber plugs (CVM) by using the
vitrification solutions described by Vajta et al. [31].
Briefly, embryos were first handled in a basic vitrification
medium (BV), consisting of TCM 199-HEPES
20% FCS. All procedures were performed in a warm
room (30 °C) on a heated surface (41 °C).