Macaque sperm fusion with zona-free hamster oocytes

Semen from six cynomolgus macaques was washed twice by centrifugation in BWW media and resuspended in 1:2 (vol:vol) of Tes-Tris-buffered eggyolk extract (EXT) diluent and BWW (EXT-BWW). Caffeine and dbcAMP were added to induce capacitation. Sperm were treated with calcium ionophore, A23187, followed by the addition of EXT to recover motility, then washed into BWW. The percent motile sperm was similar in ionophore-treated and control sperm suspensions, but motility of treated sperm decreased significantly by 20 min after treatment. The percentage of viable, acrosome-reacted sperm was 56.3% following ionophore treatment versus 4.0% in control suspensions. When ionophore-treated sperm were coincubated with zona-free hamster oocytes, 51% of oocytes had evidence of sperm fusion and no oocytes were penetrated after incubation with control sperm. These results are consistent with the hypothesis that macaque sperm are capable of fusion with zona-free hamster oocytes if sperm are viable and acrosome-reacted.