THE EFFECT OF EGG-YOLK MEDIUM ON HUMAN SPERM BINDING IN THE HEMIZONA ASSAY

Objective: To evaluate, using the hemizona assay (HZA), whether egg yolk treatment of human sperm enhances binding to the human zona pellucida in vitro and to determine whether such a treatment is as efficient as the standard swim-up procedure for promoting sperm binding ability. Design: Ejaculates were divided into aliquots and half incubated at 37-degrees-C for 21 hours in standard culture medium or combined with buffered medium containing chicken egg yolk and stored at 4-degrees-C for 21 hours. A second set of ejaculates were split and processed by a standard 1-hour rise alone or treated with egg yolk medium. Setting: University teaching hospital. Participants: Two healthy sperm donors. Main Outcome Measure: The number of sperm tightly bound to the hemizona were measured and compared between the groups. Results: A significant increase (P < 0.0001) in hemizona binding (n = 46) for egg yolk treatment (90.1 +/- 9.8; range 7 to 258) as compared with standard culture medium (53.0 +/- 8.8; range 0 to 228) was observed. Similarly, a significant increase (P < 0.0001) in binding (n = 37) for egg yolk treatment (74.9 +/- 8.2; range 7 to 219) as compared with samples obtained with a sperm rise (37.1 +/- 5.7; range 2 to 122). Conclusions: Treatment of human spermatozoa with an egg yolk medium at 4-degrees-C overnight significantly increases sperm binding in the HZA.