Cryopreservation of spermatozoa from cynomolgus monkeys (Macaca fascicularis)

Fertilization of eggs from cynomolgus monkeys (Macaca fascicularis) was achieved in vitro using frozen-thawed spermatozoa. The best sperm survival rate was obtained after freezing spermatozoa in a semen-diluting medium (TTE: Tes, Tris, egg yolk base) containing 5% glycerol with 30 min equilibrium time. Although frozen-thawed spermatozoa could fertilize eggs in vitro and some of the fertilized eggs developed into blastocysts or hatched blastocysts, a sperm fertility assay using salt-stored eggs indicated that frozen-thawed spermatozoa had a shorter lifespan in capacitation medium than did fresh, unfrozen spermatozoa. This may be attributable to damage to their plasma membranes.