DEVELOPMENT OF A PREDICTIVE MODEL FOR OPTIMAL ZONA-PELLUCIDA BINDING USING INSEMINATION VOLUME AND SPERM CONCENTRATION

Objective: To develop a predictive model under hemizona assay (HZA) co nditions for human spermatozoa concentrations and insemination volume for optimum zona pellucida (ZP) binding. Design: Analysis of 20 differ ent insemination volumes for zona binding and sperm morphology under H ZA conditions. Setting: Reproductive biology unit, tertiary medical ce nter. Patients: Four proven fertile sperm donors. Main Outcome Measure s: 5-, 20-, 50-, 80-, and 100-mu L droplets were analyzed with four di fferent concentrations of 0.5 X 10(6), 1.0 X 10(6), 2.0 X 10(6), and 4 .0 X 10(6) cells/mL to determine the number of sperm bound to each hem izona. Fifteen hemizonae were used for each insemination volume or mic rodroplet. Response surface regression model with volume and concentra tion as the regressor variables has been used. Results: The response s urface of binding for the factors concentration and volume showed nonl inear association. A formula, indicating the optimal sperm inseminatio n volume for maximum sperm binding to the ZP, V-max = -(b(1) + b(5)c)/ 2b(6)c, is described. The transformed data indicated 60 mu L containin g 4 X 10(6) sperm/mL to be optimal. Although morphology of zona sperma tozoa is superior compared with seminal and postswim-up samples, no di fference among the percentage of the normal morphology in different mi crodroplets could be demonstrated. Conclusion: Optimal volume for the obtained concentration of spermatozoa from a patient can be calculated and therapeutically used for cases of severe oligozoospermic patients by microvolume inseminations in IVF practice.