Development of Rapid-i vitrified –warmed embryos. Images of human embryos vitrified on Day 3 at the 8–10 cell stage using the Rapid-i carrier (a,b) Morphology immediately after warming, (c,d) Morphology after 24 hours of culture. Both embryos show signs of embryonic compaction and resumption of mitosis, (e,f) Embryos progressed to the blastocysts stage after 48 hours in culture. Transfer resulted in a twin pregnancy. Magnification 300 ×.