Relevance of acrosome function in the evaluation of semen in vitro fertilizing ability

To determine whether or not acrosome evaluation can enhance the prediction of IVF results when associated to conventional semen parameters.

Acrosome reaction, sperm concentration, motility, and morphology were recorded in 131 semen samples from patients undergoing an IVF attempt.

Spontaneous acrosome loss after a 24-hour incubation in B2 medium and after induction by calcium ionophore A23187 and phorbol ester, phorbol 12-myristate 13-acetate 4-O-methyl ether (TPA).

Statistically significant differences between fertilization failures and successes were found for concentration, viability, spontaneous and induced acrosome reaction, and most parameters of motility and morphology. However, none of the parameters could predict > 64% of IVF results when studied alone. A progressive discriminant analysis allowed to predict up to 83% of IVF results, by classifying sperms through their normal forms, rapid motility, spontaneous acrosome loss, enlarged heads, multiflagellar forms, vitality, linear motility, and acrosome response to TPA. The other parameters, including concentration and response to calcium ionophore, had no additive value.

The study of acrosome function, through spontaneous acrosome loss and response to TPA, is of great interest in clinical practice when associated to some parameters of motility and morphology. However, it appears that response to calcium ionophore, one of the most studied parameters, is of poor practical interest.