title: Spindle configuration and developmental competence of in vitro-matured bovine oocytes exposed to NaCl or sucrose prior to Cryotop vitrification.
abstract: In the present study we examined whether exposure to high concentrations of NaCl or sucrose before vitrification improves the cryotolerance of in vitro-matured bovine oocytes. In Experiment 1, oocytes were exposed to different concentrations of NaCl (375-1517 mOsm) or sucrose (375-812 mOsm) for 1 h. On the basis of the results of this experiment, in Experiment 2 oocytes were exposed to 0.25% NaCl (375 mOsmol) or 2.77% sucrose (375 mOsmol) solution, vitrified and warmed. Microtubule and chromosome configurations were examined by immunocytochemistry. In Experiment 3, in vitro embryo development was assessed after vitrification of oocytes with or without 2.77% sucrose (375 mOsmol) pretreatment. There was a similar percentage of oocytes showing normal spindle configurations in the sucrose-pretreated and control groups. Higher rates of abnormal spindles were found in groups treated with NaCl or sucrose solutions with >375 mOsmol. After vitrification and warming, a significantly higher percentage of oocytes with normal chromosome configurations was recorded for oocytes exposed to 375 mOsmol sucrose solution before vitrification compared with the control vitrified oocytes. However, these percentages were significantly lower than those recorded in untreated controls. Cleavage and blastocyst rates were higher in non-vitrified than vitrified oocytes. In conclusion, pretreatment with 375 mOsmol NaCl or sucrose solution had no adverse effects on the spindle status of vitrified-warmed cow oocytes. However, sucrose pretreatment offered no benefits for embryo development.
authors.affiliation: Department of Animal Medicine and Surgery, University Autonomous of Barcelona, Campus UAB, 08193 Cerdanyola del Vallès, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Arcarons
authors.affiliation: Department of Biology, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: Roser
authors.initials: R
authors.lastname: Morató
authors.affiliation: School of Agriculture and Veterinary Medicine, University of Brasilia, CEP 70910-900, Brasília-DF, Brazil.
authors.forename: Jozé F W
authors.initials: JFW
authors.lastname: Spricigo
authors.affiliation: Department of Farm Animal Health, University of Utrecht, 3584 CM Utrecht, The Netherlands.
authors.forename: Marcia A M M
authors.initials: MAMM
authors.lastname: Ferraz
authors.affiliation: Department of Animal Medicine and Surgery, University Autonomous of Barcelona, Campus UAB, 08193 Cerdanyola del Vallès, Spain.|Corresponding autor. Email: teresa.mogas@uab.cat.
authors.forename: Teresa
authors.initials: T
authors.lastname: Mogas
keywords: blastocyst; chromosomes; embryo development; microtubule configuration; osmotic stress