The influence of human follicular fluid on the acrosome reaction, fertilizing capacity and proteinase activity of human spermatozoa.

The present study was designed to assess physiological and enzymatic changes in human spermatozoa following incubation in human follicular fluid (HFF). Initially, it was determined that infertility patients (n = 29) scored dramatically higher on the hamster egg penetration test (HEPT) when spermatozoa were incubated with HFF (22.9 +/- 4.4%) rather than the standard swim-up alone (4.6 +/- 1.1%). To further evaluate this effect, in experiment I, spermatozoa were obtained from proven fertile individuals and evaluated following exposure to three different HFF samples as well as control treatments (medium, cul de sac fluid and heparin). There were no significant differences in HEPT scores following sperm incubation in the three different follicular fluids although incubation in all the fluids significantly (P less than 0.01) enhanced sperm penetration (%PEN) when compared to the standard swim-up and other control treatments. The absence of an effect of cul de sac fluid on spermatozoa indicates that not all body fluids contain factors which stimulate sperm fertilizing capacity. The effect of HFF was demonstrated in a infertile patient population as well as in donors of proven fertility. In experiment II, the effect of HFF on the acrosome reaction (%AR), sperm fertilizing capacity and changes in sperm proteolytic enzymes were determined. There was no significant difference in the %AR between freshly ejaculated (7.9 +/- 3.1) and medium incubated (9.4 +/- 1.6) spermatozoa; however, in both of these treatments the %AR was less (P less than 0.01) than for spermatozoa treated with HFF (45.6 +/- 4.7). The %PEN following incubation of spermatozoa in HFF (52.2 +/- 6.8) was greatly increased (P +/- 0.01) compared to the standard swim-up (19 +/- 3.9).