title: Mitochondrial distribution after fast embryo freezing.
abstract: Mitochondrial distribution pattern after ultrarapid freezing in dimethylsulphoxide was assessed in human multipronucleate zygotes, 2-cell and 4-cell stage embryos using rhodamine 123. The mitochondrial distribution pattern was evaluated at 37 degrees C after a 30 min incubation in rhodamine 123 solution, 4 h and 24 h after thawing. Non-frozen human unfertilized oocytes, 2-cell and 4-cell embryos used as a control showed a homogeneous distribution of mitochondria throughout the cytoplasm, while there was sequestration of mitochondria from the cortex to the region surrounding the pronuclei in multipronucleate zygotes. Morphologically intact multipronucleate zygotes, 2-cell and 4-cell stage embryos after quick freeze-thawing showed the same mitochondrial distribution pattern found in the unfrozen controls. Mitochondria exhibited a typical severe aggregation (clumping) throughout the cytoplasm when non-viable single blastomeres or embryos at thawing were exposed to rhodamine 123. Our study indicates that quick freezing does not affect subcellular structures. The well-organized and specific mitochondrial distribution appeared still to be present after frozen storage, and subcellular structures seemed to be rather resistant targets for cryo-injury.
authors.affiliation: Medical Centre for Fertility Diagnostics and In Vitro Fertilization and Embryo Transfer, Leuven, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Noto
authors.forename: R
authors.initials: R
authors.lastname: Campo
authors.forename: P
authors.initials: P
authors.lastname: Roziers
authors.forename: K
authors.initials: K
authors.lastname: Swinnen
authors.forename: M
authors.initials: M
authors.lastname: Vercruyssen
authors.forename: S
authors.initials: S
authors.lastname: Gordts
mesh_terms: D002970:Cleavage Stage, Ovum / Q000648:ultrastructure*; D015925:Cryopreservation; D005260:Female; D006801:Humans; D008928:Mitochondria / Q000648:ultrastructure*; D009865:Oocytes / Q000648:ultrastructure*; D013997:Time Factors; D015053:Zygote / Q000648:ultrastructure*