Female age does not affect the capacity of human zona pellucida to bind spermatozoa.

The purpose of this study was to evaluate the effect of female age on the capacity of the zona pellucida to bind spermatozoa. A total of 1008 unfertilized oocytes obtained from 210 women (aged 21-43 years) participating in the in-vitro fertilization programme were tested using a hemizona assay. Spermatozoa taken from a cryopreserved pool of fertile donor specimens served as a control in the hemizona assay, and were used to assess the ability of the zona pellucida to bind spermatozoa. The mean +/- SD number of spermatozoa attached to the hemizona was 107 +/- 42. The binding capacity of different oocytes from the same cohort varied substantially (coefficient of variation = 28%). Age was not found to be correlated with the number of spermatozoa bound to the zona pellucida (r = -0.02; P > 0.1). It was concluded that female age has no role in the ability of the human zona pellucida to bind spermatozoa.