title: HIGH INCIDENCE OF POLYSPERMIC FERTILIZATION IN BOVINE OOCYTES MATURED IN VITRO AFTER CRYOTOP VITRIFICATION.
abstract: BACKGROUND
  Vitrification with the Cryotop device is the most promising technique for oocyte cryopreservation, but the high post-warming morphological survival of bovine oocytes does not guarantee high developmental competence after in vitro fertilization (IVF).
  
  
  OBJECTIVE
  This study was designed to examine achievement of normal fertilization in bovine oocytes vitrified-warmed with the Cryotop device.
  
  
  METHODS
  Oocytes were matured in vitro and vitrified-warmed after complete removal of the cumulus layers. Distribution of cortical granules (CGs) was assessed by Lens culinaris agglutinin (LCA) lectin staining. Ten hours after IVF, presumptive zygotes were analyzed for pronuclear formation. Day-8 blastocysts were harvested and stained with Hoechst-33342 for total cell counting.
  
  
  RESULTS
  Both yield and mean cell number of the blastocysts were impaired by Cryotop vitrification. Incidence of polyspermic fertilization was three-times higher in vitrified oocytes compared to fresh oocytes. No difference in CG distribution was found between vitrified and fresh oocytes.
  
  
  CONCLUSIONS
  Polyspermic fertilization induced in vitrified-warmed bovine oocytes may be one of the possible causes responsible for their low developmental potential.
authors.affiliation: Animal Biotechnology Division, National Institute of Animal Science, Rural Development Administration, Jeollabuk-do, Republic of Korea.
authors.forename: In-Sul
authors.initials: IS
authors.lastname: Hwang
authors.affiliation: Animal Biotechnology Division, National Institute of Animal Science, Rural Development Administration, Jeollabuk-do, Republic of Korea.
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Kwon
authors.affiliation: Animal Biotechnology Division, National Institute of Animal Science, Rural Development Administration, Jeollabuk-do, Republic of Korea.
authors.forename: Gi-Sun
authors.initials: GS
authors.lastname: Im
authors.affiliation: Faculty of Textile Science and Technology, Shinshu University, Nagano 386-8567, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Tashima
authors.affiliation: Faculty of Textile Science and Technology, Shinshu University, Nagano 386-8567, Japan. shochi@shinshu-u.ac.jp.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hochi
authors.affiliation: Animal Biotechnology Division, National Institute of Animal Science, Rural Development Administration, Jeollabuk-do, Republic of Korea. hwangss@korea.kr.
authors.forename: Seongsoo
authors.initials: S
authors.lastname: Hwang
mesh_terms: D000818:Animals; D002417:Cattle; D005306:Fertilization; D005307:Fertilization in Vitro / Q000662:veterinary*; D006358:Hot Temperature; D009865:Oocytes / Q000502:physiology*; D058989:Vitrification