Biologic variability of sperm DNA denaturation in infertile men

Objectives. To examine sperm DNA denaturation (DD) in fertile and infertile men and assess the variability of conventional semen parameters and sperm DD in repeated semen samples from infertile men. Methods. Twenty-one consecutive nonazoospermic, infertile men each submitted two semen samples, 2 to 6 weeks apart. We examined semen samples from consecutive fertile men (n = 10) presenting for vasectomy as controls. Standard semen parameters (World Health Organization criteria) and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa and expressed as the percentage of spermatozoa with denatured DNA) were monitored. Results. Fertile men had a significantly higher sperm concentration and percentage of sperm motility and a significantly lower percentage of sperm with DD than did infertile men (36 ± 5.2 × 10 6/mL versus 12.5 ± 2.2 × 10 6/mL, 60.0% ± 5.2% versus 30.1% ± 4.1%, and 8.9% ± 1.9% versus 20.3% ± 2.5%, respectively, P