Zona pellucida induced acrosome reaction, sperm morphology, and sperm-zona binding assessments among subfertile men
Purpose: The study aimed to evaluate the relationship between the zona pellucida induced acrosome reaction (ZIAR) and (i) percentage normal spermatozoa as well as (ii) sperm-zona pellucida binding potential among men referred for a routine semen analysis. Methods: Semen samples of 164 consecutive men referred to the andrology laboratory for routine semen analysis were studied. Semen samples were analyzed using the new WHO standards (strict criteria). ZIAR was recorded with a lectin conjugated Pisum sativum agglutinin microassay, while sperm-zona binding was evaluated with a standard hemizona assay (HZA). Results: Andrology patients were divided according to the percentage normal spermatozoa in the ejaculate, namely <4% normal forms (n = 71), 5-14% normal forms (n = 73), and >14% normal forms (n = 20). ZIAR data of the <4%, 5-14%, and >14% groups was (9.6 ± 0.6)%, (13.9 ± 0.5)%, and (15.0 ± 1.1)%, respectively. The ZIAR data of fertile control men was (26.6 ± 1.4)% which differed significantly from the three andrology referrals groups. Likewise significant differences were recorded during the hemizona assay namely, 38.0% (<4% normal forms), 54.5% (5-1% normal forms), and 62.6% (>14% normal forms). Among the group with >14% normal forms, five cases had impaired ZIAR outcome (<15%). Three of these men had normal morphology and HZAs. Conclusions: ZIAR testing should become part of the second level of male fertility investigations, i.e., sperm functional testing, since 15% of andrology referrals revealed an impaired acrosome reaction response to solubilized zona pellucida.