Elaboration of a new culture medium for physiological studies on human sperm motility and capacitation.

The formulation of a new medium based upon published data on human tubal fluid and blood plasma is described. Sperm motility was well maintained for periods of up to 6 h in this 'synthetic tubal fluid' (STF), and movement characteristics (velocity of progression and amplitude of lateral head displacement) were quantitatively and qualitatively similar to values previously reported for other complex media. STF also supported human sperm capacitation and the spontaneous acrosome reaction as determined using the zona-free hamster egg penetration test. Spermatozoa pre-incubated in STF containing blood plasma levels of taurine (86 microM) for 3 h penetrated significantly more oocytes than parallel sperm populations pre-incubate in STF lacking taurine (P less than 0.001). This difference was no longer significant after 5 h of pre-incubation. These findings indicate a possible role for taurine in human sperm capacitation, and demonstrate the potential value of STF for performing more physiological invitro studies on human sperm function.