THE EFFECT OF EGG-YOLK AN THE BINDING-CAPACITY OF HUMAN SPERMATOZOA TO ZONA-PELLUCIDA

Objective: To evaluate the effects of Tea and Tris (TEST)-yolk buffer (TYB) incubation on sperm function. Design: Sperm samples obtained fro m 61 patients attending the infertility clinic were incubated in TYB a nd control medium. Binding to the zona pellucida (ZP), evaluated by th e hemizona assay, membrane functional integrity evaluated by the hypoo smotic swelling test, and acrosome reaction and penetration through ce rvical mucus were assessed to ascertain the effect of TYB treatment. R esults: The only substantial effect of TYB treatment was enhanced sper m binding to the ZP. The mean number of sperm cells attached to the he mizonae with TYB or medium treatment, was 42 +/- 6.1 (+/-SE) and 31 +/ - 5.8, respectively (n = 61). However, this improvement was most obvio us in 12 patients whose sperm samples exhibited a marked increase in s perm binding capacity following TYB treatment compared to medium witho ut TYB, 71 +/- 5.6 and 12 +/- 2.7, respectively. In the other sperm sa mples (n = 49), sperm binding capacity was similar following TYB and m edium treatment (both 35 +/- 6.0). Conclusions: A 2-hour incubation of sperm samples with TYB-containing medium (at room temperature) enhanc es the binding capacity of human spermatozoa in approximately 20% of p atients considered to have male factor infertility. The basis of this selective effect has yet to be studied further.