High frequency of defective sperm-zona pellucida interaction in oligozoospermic infertile XXXX .

@entity1 @entity137
BACKGROUND: The ability of sperm to interact with the zona pellucida (ZP) plays a critical role during the process of @entity1 fertilization. The aim of this study is to determine frequency of defective sperm-ZP interaction in oligozoospermic infertile @entity1 . METHODS: Sperm-ZP binding assays and the ZP-induced @entity137 ( @entity137 ) were performed in 72 infertile @entity1 with a sperm concentration <20 x 10(6)/ml. Oocytes that had previously failed to fertilize in a clinical IVF programme were used for the tests. Motile sperm (2 x 10(6)/ml) selected by swim-up from each semen sample were incubated with four oocytes for 2 h. The number of sperm bound per ZP and the ZP-induced @entity137 were assessed. Under these conditions, an average of < or =40 sperm bound/ZP was defined as low sperm-ZP binding and a ZP-induced @entity137 < or =16% was defined as low ZP-induced @entity137 . RESULTS: In the 72 oligozoospermic @entity1 , 28% (20/72) had low sperm-ZP binding. Of those with normal sperm-ZP binding, 69% (36/52) had low ZP-induced @entity137 . Overall, 78% (56/72) had either low ZP-binding or normal ZP binding but low ZP-induced @entity137 . This means that only 22% (16/72) had both normal sperm-ZP binding and normal ZP-induced @entity137 . CONCLUSION: Oligozoospermic @entity1 have a very high frequency of defective sperm-ZP interaction, consistent with their low natural fertility or low fertilization rate in conventional IVF. Infertile couples with oligozoospermic semen should be treated by ICSI rather than by conventional IVF.
