Artificial induction of the acrosome reaction in human spermatozoa.

This study investigated the use of human follicular fluid and pentoxifylline as inducers of the human sperm acrosome reaction in vitro. Motile sperm suspensions were prepared using a discontinuous Percoll gradient, preincubated for 3 h, divided into aliquots and exposed to various concentrations of non-heat-inactivated follicular fluid for 1 and 24 h and pentoxifylline for 30 min. Detection of the acrosome reaction involved the combined use of a fluorescent vital stain, H33258, and fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA). A short (1 h) exposure to follicular fluid at concentrations of 50% or more, did not compromise sperm motility and significantly increased the proportion of spermatozoa having completed the acrosome reaction. Similarly, a 30 min exposure to pentoxifylline also significantly increased the proportion of spermatozoa having completed the acrosome reaction.