Bovine oocyte vitrification: effect of ethylene glycol concentrations and meiotic stages.
Success in oocyte cryopreservation is limited and several factors as cryoprotectant type or concentration and stage of oocyte meiotic maturation are involved. The aim of the present study was to evaluate the effect of maturation stage and ethylene glycol (EG) concentration on survival of bovine oocytes after vitrification. In experiment 1, kinetics of oocyte in vitro maturation (IVM) was evaluated. Germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase I (MI), and metaphase II (MII) oocytes were found predominantly at 0, 0-10, 10-14, and 18-24h of IVM, respectively. In experiment 2, in vitro embryo development after in vitro fertilization (IVF) of oocytes exposed to equilibrium (ES) and vitrification solution VS-1 (EG 30%), or VS-2 (EG 40%) at 0, 12 or 18 h of IVM was evaluated. Only blastocyst rate from oocytes vitrified in SV-2 after 18 h of IVM was different from control oocytes. Hatched blastocyst rates from oocytes vitrified in VS-1 after 12 and 18 h, and SV-2 after 18 h of IVM were different from unvitrified oocytes. In experiment 3, embryo development was examined after IVF of oocytes vitrified using VS-1 or VS-2 at 0, 12 or 18 h of IVM. Rates of blastocyst development after vitrification of oocytes in VS-1 at each time interval were similar. However, after vitrification in VS-2, blastocyst rates were less at 18 h than 0 h. Both cleavage rates and blastocyst rates were significantly less in all vitrification groups when compared to control group and only control oocytes hatched. In conclusion, both EG concentration and stage of meiotic maturation affect the developmental potential of oocytes after vitrification.
University of São Paulo, Faculty of Veterinary Medicine, Department of Animal Reproduction, São Paulo, SP, Brazil.
Vanessa
V
Magnusson
Weber Beringui
WB
Feitosa
Marcelo Demarchi
MD
Goissis
Claudia
C
Yamada
Liliam Mara Trevisan
LM
Tavares
Mayra Elena Ortiz
ME
D'Avila Assumpção
José Antonio
JA
Visintin
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002467:Cell Nucleus / Q000187:drug effects; D002470:Cell Survival; D002478:Cells, Cultured; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000009:adverse effects / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019855:Ethylene Glycol / Q000009:adverse effects / Q000494:pharmacology*; D005260:Female; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology; D009994:Osmolar Concentration
D003451:Cryoprotective Agents; D019855:Ethylene Glycol