Factors affecting the survival of frozen-thawed mouse spermatozoa

Mouse epididymal spermatozoa were frozen in solutions containing various co mpounds with different molecular weights, and the factors affecting the pos tthawing survival were examined. Monosaccharides (glucose, galactose) had a lmost no protective effect regardless of the concentration and the temperat ure of exposure. On the other hand, disaccharides (sucrose, trehalose) and trisaccharides (raffinose, melezitose) resulted in higher survival rates, e specially at a concentration of around 0.35 mol/kg H2O (0.381-0.412 Osm/kg) . Macromolecules, such as PVP10, Ficoll 70, bovine serum albumin, and skim milk had almost no effect, but compounds with a molecular weight of about 8 00, such as metrizamide and Nycodenz, had some protective effect. When a ra ffinose solution was supplemented with 10% metrizamide, resulting in an osm olality of similar to 0.400 Osm/kg, a high survival rate was obtained. Solu tions at about 0.400 Osm/kg containing trehalose alone, trehalose + metriza mide, raffinose alone, and raffinose + metrizamide, were all effective for sperm freezing; frozen-thawed sperm could fertilize oocytes, and the result ant embryos could develop to live young after transfer. For freezing mouse spermatozoa, aqueous solutions at similar to 0.400 Osm/kg containing a disa ccharide or a trisaccharide seem to be effective. (C) 2000 Academic Press.