title: Cryopreservation of human embryos and oocytes.
abstract: The success rate of human embryo cryopreservation depends on technical and embryonic parameters. First of all, the cryoprotectant can affect embryo survival as we found by comparing two freeze-thaw procedures using propanediol (PROH) (1.5 mol) alone or with sucrose (0.1 mol). Embryo survival was significantly enhanced with sucrose (62 versus 32%). Embryo quality is another major parameter involved in the success of freezing; the rates of positive survival were found to be 67% for morphologically normal embryos versus 49% for embryos with fragments (P less than 0.001). The efficiency of embryo cryopreservation in an IVF programme could be estimated in 1986: a woman with extra embryos, stored after transfer of 3-4 fresh embryos (16% of all cycles), can expect a 22% pregnancy rate per transfer of fresh embryos and a 32% pregnancy rate per collection after transfer of the stored eggs. A comparative study of the cryopreservability of immature or mature oocytes was performed in humans. Human oocytes have a low survival rate (36%) whatever the cryopreservation protocol or the initial maturation stage. Immature human oocytes could survive freezing and thawing, mature and be fertilized in vitro, but with a very low efficiency.
authors.affiliation: U. 173 INSERM, Hôpital Necker, Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Mandelbaum
authors.forename: A M
authors.initials: AM
authors.lastname: Junca
authors.forename: M
authors.initials: M
authors.lastname: Plachot
authors.forename: M O
authors.initials: MO
authors.lastname: Alnot
authors.forename: J
authors.initials: J
authors.lastname: Salat-Baroux
authors.forename: S
authors.initials: S
authors.lastname: Alvarez
authors.forename: C
authors.initials: C
authors.lastname: Tibi
authors.forename: J
authors.initials: J
authors.lastname: Cohen
authors.forename: C
authors.initials: C
authors.lastname: Debache
authors.forename: L
authors.initials: L
authors.lastname: Tesquier
mesh_terms: D004624:Embryo Transfer; D004622:Embryo, Mammalian; D005260:Female; D005307:Fertilization in Vitro; D005615:Freezing; D006801:Humans; D009865:Oocytes; D011247:Pregnancy; D011309:Preservation, Biological / Q000379:methods*