Impact of Presence or Absence of Trehalose during Vitrification on Viability and Development of Vitrified/Warmed Immature Dromedary Camel Oocytes

摘要

Vitrification of immature oocytes at the germinal vesicle (GV) stage is important to preserve female gametes. The standard formula for vitrification solutions has long been a debate. Herein, we investigated the effect of the presence or absence of trehalose in vitrification solution on viability, in vitro maturation (IVM) rates, and development of vitrified/warmed immature dromedary camel oocytes. Cumulus oocyte complexes (COCs) obtained at slaughter from the ovaries of mature she-camels were randomly allocated into three groups;namely, control group, oocytes were directly subjected to IVM without vitrification, vitrification solution 1 (VS1) group, oocytes were vitrified in a solution composed of 25% ethylene glycol (EG) plus 25% dimethyl sulfoxide (DMSO) + 0.5 M trehalose;and vitrification solution 2 (VS2) group, oocytes were vitrified in a solution composed of 25% EG plus 25% DMSO. Vitrification of COCs was conducted by open pulled straws (OPS) method. Following vitrification and warming, morphologically viable oocytes were matured in vitro for 36 h. COCs were then fertilized and cultured in vitro for 7 days. The percentage of viable oocytes was significantly higher (P 0.05) in VS2 than VS1 group (80.0% vs. 63.3%, respectively). Nuclear maturation, cleavage (48 h post-insemination;pi), and blastocyst rates (7 days pi) were significantly higher (P < 0.05) in VS2 than in VS1 groups. No significant differences were observed in oocyte maturation and development rates between VS2 and control groups. In conclusion, vitrification of immature dromedary camel oocytes in trehalose-free solution (VS2) was more advantageous than that in trehalose supplemented media since it did not reduce viability and development.