Incidence of Fas positivity and deoxyribonucleic acid double-stranded breaks in human ejaculated sperm.

To determine the incidence of Fas positivity and DNA double-strand breaks (DSB) as indicators of early- and late-stage apoptosis in ejaculated sperm. Fas positivity was assessed by flow cytometry and DSB by the neutral Comet assay. Andrology Laboratory, Royal Maternity Hospital, Belfast, Northern Ireland, United Kingdom. Forty-five infertile men undergoing infertility investigations and 10 fertile men undergoing vasectomies. Percentage Fas-positive cells, percentage DNA fragmentation, olive tail moment. The apoptotic marker Fas was detected in ejaculated sperm, with a higher incidence of Fas positivity in teratozoospermic and asthenozoospermic than in normozospermic semen. No Fas positivity was observed in fertile men's sperm. Deoxyribonucleic acid fragmentation (DSB) was greater in infertile than in fertile men's sperm and also greater in sperm in semen than in sperm prepared for assisted conception. There was an inverse relationship between DSB and both sperm concentration and motility. There was no relationship between Fas positivity and DNA damage. Fas was expressed in sperm of infertile men. In contrast, DNA fragmentation was observed in all sperm of fertile and infertile men and correlated with inadequate concentration and motility, which suggests that sperm DSB are ubiquitous and are not solely associated with apoptosis.