title: High frequency of defective sperm-zona pellucida interaction in oligozoospermic infertile men.
abstract: BACKGROUND
  The ability of sperm to interact with the zona pellucida (ZP) plays a critical role during the process of human fertilization. The aim of this study is to determine frequency of defective sperm-ZP interaction in oligozoospermic infertile men.
  
  
  METHODS
  Sperm-ZP binding assays and the ZP-induced acrosome reaction (AR) were performed in 72 infertile men 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 AR were assessed. Under these conditions, an average of < or =40 sperm bound/ZP was defined as low sperm-ZP binding and a ZP-induced AR < or =16% was defined as low ZP-induced AR.
  
  
  RESULTS
  In the 72 oligozoospermic men, 28% (20/72) had low sperm-ZP binding. Of those with normal sperm-ZP binding, 69% (36/52) had low ZP-induced AR. Overall, 78% (56/72) had either low ZP-binding or normal ZP binding but low ZP-induced AR. This means that only 22% (16/72) had both normal sperm-ZP binding and normal ZP-induced AR.
  
  
  CONCLUSIONS
  Oligozoospermic men 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.
authors.affiliation: University of Melbourne Department of Obstetrics and Gynaecology, Reproductive Services, Royal Women's Hospital and Melbourne IVF, Victoria 3035, Australia. dyl@unimelb.edu.au
authors.forename: De Yi
authors.initials: DY
authors.lastname: Liu
authors.forename: H W Gordon
authors.initials: HW
authors.lastname: Baker
mesh_terms: D020101:Acrosome Reaction; D005260:Female; D006801:Humans; D008297:Male; D009845:Oligospermia / Q000503:physiopathology* / Q000628:therapy; D013076:Sperm Count; D020554:Sperm Injections, Intracytoplasmic; D013081:Sperm Motility; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology*; D015044:Zona Pellucida