[Effects of cryoprotectants and sucrose dilution on the survival of unfertilized and fertilized mouse eggs after freezing and thawing].

We have studied the methods of cryopreservation and dilution of the unfertilized and fertilized eggs of ICR mouse. To improve the survival rate, we examined 8 types of methods with various combination of cryoprotectants, dilutions and cooling rates. The highest survival rate for unfertilized eggs was obtained when 1.5 M dimethylsulfoxide (DMSO) + 0.25 M sucrose was added to PBS as a cryoprotectant and when the eggs were diluted by adding PBS with 0.5 M sucrose at room temperature at 5-minute intervals in 5 steps. The total survival rate was 45.4% (p less than 0.01). In the case of fertilized eggs, the highest survival rate (72.6%) was obtained with 10% glycerol + 0.25 M sucrose as a cryoprotectant and a One-step dilution method. The most effective cooling rate was 0.3 degrees C per minute for either unfertilized or fertilized eggs.