THE SPECIFICITY OF HUMAN SPERMATOZOA ZONA-PELLUCIDA INTERACTION UNDERHEMIZONA ASSAY CONDITIONS

The objective of this prospective study was to evaluate the specificit y of human sperm/zona pellucida interaction under hemizona assay (HZA) conditions in experiments with gametes from the same and different sp ecies. Human, cynomolgus monkey and hamster oocytes were used after sa lt-storage. Oocytes were bisected into matching hemizonae by micromani pulation and used in the HZA. Semen was obtained from healthy men (don ors) and male cynomolgus monkeys and prepared by wash and swim-up. Spe rm binding to matching hemizonae was assessed (tight binding) after 4- h coincubation in the HZA in homologous and interspecies experiments. Acrosome reaction was evaluated in the sperm droplets using FITC-PSA a nd on the hemizonae using the T-6 monoclonal antibody. On human hemizo nae, the number of tightly bound sperm for human and monkey were 93.2 +/- 15.8 and 3.9 +/- 1.3, respectively (P < 0.001). On monkey hemizona e, the number of tightly bound sperm for monkey and human were 126.0 /- 34.8 and 2.8 +/- 1.6, (P = 0.02) respectively. On hamster hemizonae , there was negligible binding of human and monkey sperm. There was a significantly higher incidence of acrosome reacted sperm on the zona p ellucida in homologous compared to heterologous experiments. These res ults demonstrate a high species-specificity of human gamete functions under HZA conditions, providing further support for the use of this bi oassay in infertility and contraception testing.