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The feasibility of cryopreservation by vitrification of Persian sturgeon (Acipenser persicus) embryos at 48 h post-fertilization stage was investigated. Vitrification is considered the most promising option. Many factors are involved in the success of the process. The choice of a proper vitrificant solutions and temperature for thawing, were the parameters considered in the present study. Six vitrificant solutions (V1-V6) were tested using a stepwise incorporation protocol. The tested solutions contained acetamide as the main cryoprotectant +3 other permeable cryoprotectants +3 non-permeable cryoprotectants. Before loading the embryos into tubes, toxicity tested was affected with these solutions. The hatching rate of embryos that had been exposed to the vitrificant solutions was analyzed and the highest hatching rate was obtained with exposure to V1. After thawing (water bath, 0 or 20°C), embryos were incubated until hatched. The highest survival rate (69.69%) was observed in samples frozen with V1 and thawed at 20°C. These results establish that cryopreservation of Persian sturgeons embryos by vitrification is possible.

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The effects of vitrification on the embryo viability of the Persian sturgeon (Acipenser persicus) were investigated in this study. Vitrificant solutions (VS1-VS6) were prepared by combining propylene glycol (PG) as basic cryoprotectant plus other permeable and non-permeable cryoprotectants in different concentration. Embryos at neurulation stage were selected and incubated in six vitrificant solutions for 7 minutes using four-step incorporation protocol before transferring into liquid nitrogen. Following these treatments, the embryos were washed well and incubated until hatching. The results showed that PG-based vitrificant solutions seemed to be suitable for the vitrification of Persian sturgeon embryos except VS4. After vitrification (-196°C for 10 min), the embryos were thawed (water bath, 0 or 20°C), rehydrated and incubated to determine survival rate. Results demonstrated that the embryos treated with solutions VS1, VS2, VS3, VS5 and VS6 presented some degrees of viability after vitrification, whereas none survived after vitrification in VS4. There were no differences in the results obtained using either 0 or 20°C thawing temperatures. Among six vitrificant solutions, the combination of 6 M PG + 5 M dimethyl sulfoxide +6 M ethylene glycol +3 M acetamide (VS1) had the highest survival rate (59.09%).

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