Cryoprotectant toxicity in fish embryos

Successful fish embryo cryopreservation has not been achieved. Cryopreservation of fish embryos is replacement of cryoprotectants with water inside embryo. Cryopreservation of fish embryos requires an optimal concentration of cryoprotectants inside all embryo compartments. In researches on cryopreservation of embryo, information on relative toxicities of cryoprotectants is of key importance. Cryoprotectants are less toxic at lower temperatures. Cryoprotectants can neutralize the toxicity of other cryoprotectants. Generally the hatching rate decrease with increase in concentration and expose time. Reduced hatch may be a result of osmotic shock, ionic imbalance or consequence of cryoprotectant toxicity. As the progress of embryonic development, sensitivity of embryos decrease to the different concentration of cryoprotectants and can tolerate high concentration of this materials better.