title: Survival and pregnancy outcome after ultrarapid freezing of human embryos.
abstract: Contrary to the belief that rapid cooling and thawing of mammalian embryos is detrimental to survival, it has been shown that under certain conditions mammalian embryos can survive rapid freezing-thawing. In this study, 237 human fertilized oocytes (93 pronucleates, 20 multipronucleates, and 124 cleaved embryos) were frozen for a period of 1 day to 7 months using the ultrarapid freezing system. After thawing, 94% of the embryos in the pronucleate group and 89.5% in the multipronucleate group showed normal morphological features, and 79% and 71%, respectively, started to cleave. Forty cleaved embryos were also frozen-thawed, but only 15 (37.5%) survived at thawing. Thirty-four frozen-thawed cleaved embryos were transferred to 20 patients during spontaneous cycles. Four patients became pregnant.
authors.affiliation: Medical Center for Fertility Diagnostics and In Vitro Fertilization, Leuven, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Gordts
authors.forename: P
authors.initials: P
authors.lastname: Roziers
authors.forename: R
authors.initials: R
authors.lastname: Campo
authors.forename: V
authors.initials: V
authors.lastname: Noto
mesh_terms: D002455:Cell Division / Q000502:physiology; D002970:Cleavage Stage, Ovum / Q000502:physiology; D015925:Cryopreservation; D004121:Dimethyl Sulfoxide; D004624:Embryo Transfer / Q000379:methods*; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology*; D005260:Female; D005313:Fetal Death; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D013395:Sucrose
chemical_list: D013395:Sucrose; D004121:Dimethyl Sulfoxide