title: Double activation improves rabbit freeze-thawed oocytes developmental potential.
abstract: OBJECTIVE
  To investigate the effects of various activation methods on freeze-thawed rabbit oocytes developmental potential.
  
  
  METHODS
  Rabbit oocytes were vitrified by cryoleafs and cryoprotected with ethylene glycol and propanediol. After thawing, the oocytes were fertilized by intracytoplasmic sperm injection (ICSI). Surviving oocytes after ICSI were divided into five groups at random. Group 1: Oocytes (n = 30) activated 1 h after ICSI by calcium ionomycin (I0634); Group 2: Oocytes (n = 26) activated by strontium chloride an hour after ICSI; Group 3: Oocytes (n = 33) activated by I0634 twice; Group 4: Oocytes (n = 28) were activated by strontium chloride twice;
  
  
  METHODS
  Inactivated oocytes (n = 39). Blastocysts derived from each group were transplanted to recipient rabbits.
  
  
  RESULTS
  Rates of fertilization, cleavage and blastocyst formation of Group 3 were higher than those of Group 1 and Group 2 (81.8% vs 33.3% vs 53.8%, 54.5% vs 16.7% vs 26.9%, p < 0.05; 15.2% vs 3.3% vs 7.7%, p > 0.05). The rabbit transplanted with embryos derived from Group 3 became pregnant. Embryos derived from double activation could implant into endometrium.
  
  
  CONCLUSIONS
  Double activation may increase freeze-thawed oocytes developmental potential. After activation, oocytes cleavage velocity may be faster than that of oocytes without activation.
authors.affiliation: Reproduction Centre, First Affiliated Hospital of Anhui Medical University, Hefei, China.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Cong
authors.forename: Z G
authors.initials: ZG
authors.lastname: Zhang
authors.forename: Y X
authors.initials: YX
authors.lastname: Cao
authors.forename: Z L
authors.initials: ZL
authors.lastname: Wei
authors.forename: P
authors.initials: P
authors.lastname: Zhou
authors.forename: J H
authors.initials: JH
authors.lastname: Zhao
authors.forename: X J
authors.initials: XJ
authors.lastname: He
mesh_terms: D000818:Animals; D002455:Cell Division; D015925:Cryopreservation; D004624:Embryo Transfer; D005260:Female; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D011247:Pregnancy; D011817:Rabbits; D020554:Sperm Injections, Intracytoplasmic; D015053:Zygote / Q000166:cytology / Q000637:transplantation
chemical_list: D015759:Ionomycin