Basic Stydy in the Cryopreservation of Unfertilized and Fertilized Eggs

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The cryopreservation of fertilized mammalian eggs has been applied to various species since Whittingham reported the high survival rate of frozen-thawed fertilized mouse eggs. While a great deal of information has been generated regarding factors affecting survival of frozen-thawed mouse embryos, relatively little is known about optimal freezing and thawing methods for unfertilized mouse eggs. The aims of this study were to investigate the effect of addition of cryoprotectant and sucrose dilution on unfertilized and fertilized mouse eggs. The highest survival rate of unfertilized mouse eggs was obtained when the freezing medium contained 1.5M DMSO + 0.25M sucrose and 5-step sucrose dilution method was used. The survival rate by this method was significantly higher than the other three methods. The highest survival rate of frozen-thawed 8-cell embryos was obtained when the freezing medium contained 10% glycerol + 0.25M sucrose and one-step sucrose dilution method was used.All animals and plants have some enzymes, so -called scavengers, which protect cell against cytotoxic active oxygen. Superoxide dismutase has been found in all aerobic organs and is capable of dismuting the two molecules of the superoxide radical (O_2^-) to hydrogen peroxide and oxygen. Immunolocalization in rat ovary was investigated using rat polyclonal antibodies against Cu, Zn-SOD and Mn-SOD. Growing follicles, ovulated follicles and blood vessels also exhibited high this enzymic activity. The granulosa cells and corpora lutea showed higher amounts of Cu, Zn-SOD while the interstitial gland tissue was devoid of enzymic activity. In the ovary, theca external layer of grafian follicle demonstrated the most intense immunoperoxidase staining for Mn-SOD in nearly all specimens examined.