Frequency of defective sperm-zona pellucida interaction in severely teratozoospermic infertile men.

BACKGROUND The frequency of defective sperm-zona pellucida (ZP) interaction in teratozoospermic infertile men was investigated. METHODS Sperm-ZP binding and the ZP-induced acrosome reaction (ZPIAR) were performed in 125 infertile men with <5% of their sperm with normal morphology (strict criteria), but with a sperm count > or =20x10(6)/ml and total motility >30% in semen. Oocytes that failed to fertilize in clinical IVF were used for the tests. Four oocytes were incubated for 2 h with 2x10(6)/ml motile sperm selected by swim-up. The number of sperm bound per ZP and ZPIAR were assessed. Under these conditions, an average < or sperm bound per ZP was defined as poor sperm-ZP binding, and a ZPIAR < or = was defined as low ZPIAR. RESULTS Among 125 teratozoospermic men, 31% (39/125) had poor sperm-ZP binding. Of those without poor ZP binding, 48% (41/86) had low ZPIAR. Some 64% (28/44) with sperm counts between 20 and 60x10(6)/ml had low ZPIAR. Only 36% (45/125) had normal sperm-ZP binding and ZPIAR. CONCLUSIONS Defective sperm-ZP interaction was present in 64% of teratozoospermic infertile men: 31% had defective sperm-ZP binding, and 33% low ZPIAR. The frequency of low ZPIAR was higher in men with sperm counts between 20-60x10(6)/ml.