Effects of human follicular fluid on the capacitation and motility of human spermatozoa.

OBJECTIVE: To investigate the capacitation and motility kinetics of spermatozoa treated with human follicular fluid (FF).
DESIGN: Controlled, experimental laboratory study.
SETTING: University-based gynecology unit. PATIENT(S): Human FF was collected from women undergoing assisted reproductive treatment. Semen samples were obtained from men visiting subfertility clinics. INTERVENTION(S): Spermatozoa were incubated with human FF under various experimental conditions. Spermatozoa incubated with Earle's balanced salt solution were used as the control. MAIN OUTCOME MEASURE(S): Chlortetracycline staining patterns and sperm motility parameters. RESULT(S): The rate of capacitation in the human FF-treated spermatozoa was significantly higher than that in the control spermatozoa after 1 hour and 3 hours of treatment. The percentage of acrosome-reacted spermatozoa also was significantly higher after human FF treatment than after control treatment. These effects of human FF were dose-dependent. Human FF-treated spermatozoa maintained their velocities at the zero-hour level for 5 hours, whereas the velocities of the control spermatozoa decreased significantly after 1 hour. Human FF treatment significantly increased the beat cross-frequency above the rate at zero hour for 5 hours. The hyperactivation of the human FF-treated spermatozoa remained stable for 3 hours, whereas that of the control spermatozoa decreased significantly after 1 hour of incubation. Significantly more human FF-treated spermatozoa underwent hyperactivation than did control spermatozoa after 1 hour and 3 hours of treatment. The effects of human FF on beat cross-frequency and hyperactivation were dose-dependent. CONCLUSION(S): Human FF promotes capacitation and the acrosome reaction within a short period. It also stimulates or maintains various sperm motility parameters.