RELATIONSHIP OF SUBNORMAL SEMEN PARAMETERS AND SUBSEQUENT ZONA-PELLUCIDA THINNING FOLLOWING IN-VITRO FERTILIZATION

Infertility due to male factor has been associated with reduced implan tation rates despite normal fertilization. The mechanism responsible f or lower pregnancy rates is not known. One cause of failure to achieve pregnancy despite transfer of embryos is impairment of zona pellucida (ZP) thinning, which inhibits the embryo from hatching despite initia l cell cleavage. This study was designed to evaluate whether there is an association between the ability of the ZP to thin, as measured by Z P thickness on day of transfer, and subnormal semen parameters. Signif icant differences in ZP thickness (p < 0.05, Kruskal-Wallis) were note d according to median concentration of sperm, total motile sperm, and motile density in that these values were the highest in the group of e mbryos with the thinnest zona pellucida and lowest in the group with t he thickest zona pellucida. Thus, some factor may be missing from sper m from subnormal specimens that normally assists in zona thinning.