Studies On The Vitrification Technique Of Mouse GV Oocytes

The objective of this study was to provide an effective method to cryopreserve mouse GV oocytes.The study compared pretreatment methods, configuration of oocytes, freezing protocols,thawing methods, basic liquid and the concentration of FCS on the cryopreservation effects of mouse GV oocytes. The results as follows:1 The mouse GV oocytes were treated by different pretreatment methods.The treated oocytes were cryopreserved by OPS method,then got in vitro maturation and in vitro fertilization.According to the cleavage .rate,the effect of chemical toxicity for mouse oocytes exposed to vitrification solution in different equilibration methods was analysed.The results showed that, oocytes were exposed to EFS40 for 0.5min, lmin, 2min,3min by one-step method, the cleavage rates were 7.35%, 17.02%, 12.12%, 4.44% respectively; Exposed to EFS20 for 0.5min, lmin,2min,3min and to EFS40 for 0.5min by two-step method, the cleavage rates were 9.15%, 10.08%, 30.95%, 12.41% respectively. It appeared that the effect of two-step method was better than one-step method. The highest cleavage rate was observed when oocytes were exposed to EFS20 for 2min and EFS40 for 0.5min.2 COC and oocytes denuded by straw were vitrified and fertilized.The cleavage rate were 23.17%, 30.96 %. It did not differ among the two group (P＞0.05). There were significant difference between treated group and control group (P＜0.01).3 Mouse denuded oocytes were vitrified by straw method, OPS method and GMP method. the cleavage rate did not differ between OPS method (33.07%) and GMP method(33.85%) (P＞0.05), but GMP method was better than OPS method. There were significant difference between both of the two method and straw method (10.37%) (P＜0.01). There were significant difference between treated group and control group (P＜0.01 ).4 Oocytes which vitrified by OPS method were thawed by one-step, two-step, three-step method respectively. The results showed that, the higher cleavage rate was observed during two-step method(33.62%) and three-step method (35.55%), there wasn't statistical difference between the two group (P＞0.05).5 We used DMEM and DPBS as basic liquid for mouse GV oocytes vitrification separately. According to the cleavage rate, there wasn't statistical difference between DMEM (31.25%) group andDPBS (30.28%) group (P＞0.05).6 We added different concentration of FCS to the liquid of vitrification, the results showed that,there was significant difference between 20% FCS group (33.58%) and none FCS group (6.92%) (P＜0.01) ,there was statistical difference between 20% FCS group (33.58%) and 10% FCS group(21.09%) (0.01＜P＜0.05) ,there wasn't statistical difference between 20% FCS group (33.58%) and 30% FCS group(23.66%) (P＞0.05).