Aim: To establish a method for cynomolgus monkey sperm cryopreservation in a chemically defined extender.

Methods: Semen samples were collected by electro-ejaculation from four sexually mature male cynomolgus monkeys. The spermatozoa were frozen in straws by liquid nitrogen vapor using egg-yolk-free Tes-Tris (mTTE) synthetic extender and glycerol as cryoprotectant. The effects of glycerol concentration (1%, 3%, 5%, 10% and 15% [v/v]) and its equilibration time (10 min, 30 min, 60 min and 90 min) on post-thaw spermatozoa were examined by sperm motility and sperm head membrane integrity.

Results: The post-thaw motility and head membrane integrity of spermatozoa were significantly higher (P<0.05) for 5 % glycerol (42.95±2.55 and 50.39±2.42, respectively) than those of the other groups (1 %: 19.19±3.22 and 24.84±3.64; 3 %: 34.23±3.43 and 41.37±3.42; 10 %: 15.68±2.36 and 21.39±3.14; 15 %: 7.47±1.44 and 12.90±2.18). The parameters for 30 min equilibration (42.95±2.55 and 50.39±2.42) were better (P<0.05) than those of the other groups (10 min: 31.33 3.06 and 38.98± 3.31; 60 min: 32.49±3.86 and 40.01±4.18; 90 min: 31.16±3.66 and 38.30±3.78). Five percent glycerol and 30 min equilibration yielded the highest post-thaw sperm motility and head membrane integrity.

Conclusion: Cynomolgus monkey spermatozoa can be successfully cryopreserved in a chemically defined extender, which is related to the concentration and the equilibration time of glycerol.

Keywords: cryopreservation, Macaca fascicularis, chemically defined extender, glycerol

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