The Ronald O. Perelman and Claudia Cohen "Center for Reproductive Medicine" - of Weill Cornell Medical College

Cryopreservation

Oocytes retrieved during fertility preservation treatments and embryos resulting from in vitro fertilization cycles are frozen (cryopreserved) and stored at CRM's Embryology Laboratory until they are needed.

CRM's ultrarapid freezing (vitrification) technique has replaced traditional slow-freezing and is used to cryopreserve all oocytes and embryos. Since the introduction of vitrification, post-thaw oocyte and embryo survival rates have improved from 70% to 90%, with blastocyst (five-day-old embryo) pregnancy rates increasing from 30% to 50%, identical to the pregnancy rates with "fresh" (unfrozen) blastocysts. 

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Above, L-R: Two oocytes contracting as they are vitrified (rapidly frozen). 

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Above, L-R: Expansion of an oocyte as it thaws