Human sperm-zona pellucida binding, sperm characteristics and in-vitro fertilization

The number of sperm bound to the zona pellucida (ZP) were counted on 660 oocytes that failed to fertilize in vitro from 162 patients. Oocytes from clutches in which some fertilized had significantly more sperm bound to the ZP than did those from clutches in which all oocytes failed to fertilize. Oocytes from patients in whom all were not fertilized and no sperm bound to the ZP were able to bind normal fertile donor sperm after storage in ammonium sulphate solution. The number of sperm bound to the ZP was significantly related to the proportion of sperm with normal morphology and normal intact acrosomes in semen, sperm concentration inseminated, sperm motility and viability. The number of sperm bound to the ZP, sperm normal morphology, diagnosis of male infertility and sperm concentration in semen were significantly related to the fertilization rate by logistic regression analysis. Thus the number of sperm bound to the ZP is an indicator for IVF success and low binding appears to be more frequently associated with sperm defects than oocyte defects.