This invention describes unique patterns of distribution of ganglioside GM1 in non-capacitated sperm and demonstrates that the pattern of distribution of GM1 undergoes changes that can be correlated with the process of capacitation and/or with acrosomal exocytosis. Accordingly, the present invention discloses a method for determining the ability of sperm to respond to capacitation and/or acrosomal exocytosis stimuli. The method comprises determination of distribution pattern for GM1. The method can be used for both diagnostic and predictive purposes when assessing male reproductive fitness, and can also be used to assess the effects on sperm of cryoprotective agents and protocols, and contraceptive agents.