ZONA-PELLUCIDA MEDIATED ACROSOME REACTION AND SPERM MORPHOLOGY

Sperm samples from 29 men randomly selected from the andrology laborat ory, were used to evaluate acrosome reaction response to solubilized h uman zona pellucida. Capacitated sperm samples were exposed to a solut ion containing 2 zona pellucidae (ZP) per mu l for 60 min, after which acrosomal status were recorded using a PSA-FITC technique. Controls i ncluded samples supplied by fertile sperm donors. After completion of acrosome reaction studies, patient samples were divided according to t he percentage of morphologically normal spermatozoa. Three basic group s were identified, namely, fertile donors, teratozoospermic (normal sp erm morphology 5-14%; n=25) and severely teratozoospermic (normal sper m morphology <4%; n=4) groups. The mean percent normal sperm were 15.8 +/-0.9, 10.4+/-0.7 and 2.7+/-0.7, respectively, for normozoospermic do nors? teratozoospermic and severely teratozoospermic men. The mean per centage (+/-SE) ZP mediated acrosome reacted sperm among teratozoosper mic and severely teratozoospermic cases was 25.8%+/-0.9 and 19.0%+/-0. 9 (P=0.001), compared to 36.8%+/-0.9 for the donor controls. Results w ere analysed and expressed as correlations between sperm morphology an d acrosomal response to human solubilized zona pellucida, spontaneous and calcium ionophore induced acrosome reaction. Predictive values for acrosome responsiveness were depicted with ROC curve anal)Ises. Sperm morphology evaluated by strict criteria correlated positively and hig hly significantly with the responsiveness of the acrosome reaction (r= 0.91, P=0.0001). At a morphology cut-off value of 4%, the ROC curve an alysis showed sperm morphology to be highly predictive of zona pelluci da induced acrosome responsiveness with a sensitivity of 100% and nega tive predictive value of 100%. Spontaneous and calcium ionophore induc ed acrosome reactions revealed no correlation with sperm morphology. I t was concluded that (i) morphological features of human spermatozoa a re indicative of specific functional characteristics; (ii) zona pelluc ida induction of the acrosome reaction is superior, as a predictor of sperm morphology, compared to calcium ionophore induced and spontaneou s acrosome reactions.