title: Enhanced cryosurvival of bovine blastocysts produced in vitro in serum-free medium.
abstract: OBJECTIVE
  Culture systems affect the development of IVP embryos and consequently their cryosurvival potential. The viability of postthawed bovine IVP embryos developed from IVM/IVC medium in the presence or absence of serum was compared.
  
  
  METHODS
  Cumulus-oocyte complexes were matured in IVM medium supplemented with or without serum. Some oocytes were evaluated for nuclear maturation status and others were inseminated with semen. Presumptive zygotes were cultured in IVC medium supplemented with or without serum for 9 days. Blastocysts were cryopreserved with 1.5 M ethylene glycol in PBS.
  
  
  RESULTS
  No difference was observed in the nuclear maturation status and cleavage rates in both groups, but significantly (P < 0.05) higher in blastocyst rates in the serum-supplemented group. After freezing, survival of blastocysts was higher in the serum-free group. At 36 h culture after thawing, blastocysts developed without serum had significantly (P < 0.05) higher cell number than those cultured with serum.
  
  
  CONCLUSIONS
  We conclude that serum-free culture system enhances the viability of frozen-thawed bovine embryos.
authors.affiliation: Department of Obstetrics and Theriogenology, College of Veterinary Medicine, Gyeongsang National University, Chinju, Republic of Korea.
authors.forename: Sang-Rae
authors.initials: SR
authors.lastname: Cho
authors.forename: Seong-Keun
authors.initials: SK
authors.lastname: Cho
authors.forename: Sung-Lim
authors.initials: SL
authors.lastname: Lee
authors.forename: Hyo-Jong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Sang-Yong
authors.initials: SY
authors.lastname: Choe
authors.forename: Gyu-Jin
authors.initials: GJ
authors.lastname: Rho
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D002417:Cattle; D018929:Cell Culture Techniques / Q000379:methods; D002470:Cell Survival / Q000502:physiology; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D015925:Cryopreservation; D016895:Culture Media, Serum-Free; D004624:Embryo Transfer / Q000662:veterinary; D005307:Fertilization in Vitro / Q000662:veterinary*
chemical_list: D016895:Culture Media, Serum-Free