Vitrification of Immature Swine Oocytes by the SSV Technique using Different Concentration of Cryoprotector and Exposure Time

Abstract

The present study was design to establish the optimal vitrification protocol for the immature swine oocytes using different concentration of ethylene glycol (40, 45 and 50%) in the vitrification media and different exposure time (30, 40, 50 and 60 seconds). Vitrification was performed by the SSV method in a stepwise manner. After thawing morphological and viability assessments were done. The results shows that, once the concentration of the EG and the exposure time are increased, the percentage of morphologically normal oocytes after freezing/thawing is decreasing. Meanwhile the rate of viable oocytes is increasing once the concentration of EG reaches 45% in the VM and no longer exposing the eggs then 40 seconds. It is not justified the increasing of it in the VM over 45%. At 50%, the cryoprotectant has no longer a beneficial effect in the vitrification process. High concentrations lead to cell toxicity and cell death. An acceptable vitrification protocol can be obtained only with repeated exploratory regarding to both cryoprotectant concentration and exposure time.

Keywords

• cryoprotectant
• ethylene glycol
• oocyte
• swine
• vitrification