title: Recent developments in human oocyte, embryo and blastocyst vitrification: where are we now?
abstract: The target of any cryopreservation procedure should be to ensure high survival rates of living cells after thawing. Two important parameters determine the success of any cryopreservation protocol: the manner in which cells regain equilibrium in response to cooling, and the speed of freezing (cooling rate). Slow-rate freezing protocols result in the formation of ice crystals during cooling and warming. Vitrification, in which high cooling rates in combination with a high concentration of cryoprotectant are used, does not produce any ice crystals during cooling and warming. However, there is a practical limit to the attainable cooling speed, and also a biological limit to the concentration of cryoprotectant tolerated by the cells during vitrification. Although post-warming survival depends on the species, the developmental stage and the quality of the embryos being vitrified, it seems clear that vitrification methods are increasingly successful and might be a better method than slow cooling procedures in the field of cryobiology. Many of the potential problems and benefits underlying vitrification as a method of choice for embryo cryopreservation in clinical embryology will be discussed in this review.
authors.affiliation: University of Wuerzburg, Department of Obstetrics and Gynecology, Josef-Schneider-Strasse 4, Wuerzburg 97080, Germany. juergenliebermann@hotmail.com
authors.forename: Juergen
authors.initials: J
authors.lastname: Liebermann
authors.forename: Johannes
authors.initials: J
authors.lastname: Dietl
authors.forename: Pierre
authors.initials: P
authors.lastname: Vanderzwalmen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tucker
mesh_terms: D001755:Blastocyst / Q000166:cytology*; D002470:Cell Survival; D015925:Cryopreservation / Q000379:methods* / Q000592:standards; D004624:Embryo Transfer / Q000592:standards*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods* / Q000592:standards; D006801:Humans; D009865:Oocytes