title: Comparison of slow freezing and vitrification on ovine immature oocytes.
abstract: BACKGROUND
  Immature oocytes are more sensitive to cold injury than mature oocytes.
  
  
  OBJECTIVE
  The study was to evaluate the post thaw normal oocytes, cleavage and blastocyst rates of ovine cumulus oocyte complexes (COC's) using different cryoprotectants by slow freezing and Open pulled straw (OPS) vitrification.
  
  
  METHODS
  In five replicates, abattoir derived COC's were collected and distributed into three groups. In Experiment 1, COC's were cryopreserved by a slow freezing protocol using 10% concentration of ethylene glycol (EG), 10% dimethyl sulphoxide (DMSO) or 5% EG and 5% DMSO mixture. In Experiment 2 and 3 embryos were cryopreserved by OPS vitrification using either 33% or 40% (EG, DMSO or an equal mixture of EG and DMSO mixture. Normal oocytes post thaw were in vitro matured and parthenogenetically activated.
  
  
  RESULTS
  Although, there was no difference in the number of post thaw normal oocytes between the groups, cleavage and blastocyst rates were higher in 10% slow freezing group than any of the vitrified groups.
  
  
  CONCLUSIONS
  The study demonstrates better cryopreservation of ovine COC's by controlled slow freezing than OPS vitrification.
authors.forename: M H
authors.initials: MH
authors.lastname: Bhat
authors.forename: V
authors.initials: V
authors.lastname: Sharma
authors.forename: F A
authors.initials: FA
authors.lastname: Khan
authors.forename: N A
authors.initials: NA
authors.lastname: Naykoo
authors.forename: S H
authors.initials: SH
authors.lastname: Yaqoob
authors.lastname: Ruby
authors.forename: H M
authors.initials: HM
authors.lastname: Khan
authors.forename: M R
authors.initials: MR
authors.lastname: Fazili
authors.forename: N A
authors.initials: NA
authors.lastname: Ganai
authors.forename: R A
authors.initials: RA
authors.lastname: Shah
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D019855:Ethylene Glycol / Q000494:pharmacology; D005260:Female; D005615:Freezing; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010312:Parthenogenesis; D034561:Sheep, Domestic; D013395:Sucrose / Q000494:pharmacology; D013997:Time Factors; D058989:Vitrification
chemical_list: D003451:Cryoprotective Agents; D013395:Sucrose; D019855:Ethylene Glycol; D004121:Dimethyl Sulfoxide