Zona-free hamster eggs and human sperm penetration capacity: a comparative study of proven fertile donors and infertility patients.

An in vitro penetration assay utilizing human sperm and zona-free hamster eggs was employed to evaluate human sperm fertilizing capacity for 36 patients from the infertility clinic and 9 donors of proven fertility. The infertility patients were grouped according to the normality of their semen analyses. Test results were different for the three groups: a mean penetration level +/- standard deviation of 81% +/- 26% was obtained for proven fertile donors, while a value of 14% +/- 17% was observed for infertile couples with an abnormal semen analysis. A mean +/- standard deviation penetration level of 48% +/- 33% was associated with infertile couples in which the semen analysis was normal. These groups were statistically different (P less than 0.02) when inseminations were conducted at equivalent concentrations of motile sperm. No correlation was obvious between penetration test results and any of the parameters of the semen analysis; however, penetration test results did not correlate positively with the survival index (sperm survival at the end of insemination). These results are discussed in relation to further clinical application of the test.