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Sperm genomic integrity and ultrastructural features of ejaculated spermatozoa contributing to the assessment of gamete fertility potential in patients with asthenozoospermia are discussed. The proportion of TUNEL-positive cells was significantly higher in the semen of patients with low sperm motility (n=40; p<0.01) as compared to men with normal sperm motility (n=54). Sperm DNA fragmentation negatively correlated (n=94) with sperm motility, sperm concentration, and integrity of the sperm cellular membrane (HOS-test). Two categories of patients were distinguished: (1) patients (23 out of 94 subjects) with < or = 4% of TUNEL-positive cells and (2) patients (71 subjects) with 4% of TUNEL-positive cells. A significant difference was noted in the sperm motility and HOS-test results between patients from both groups. Large numbers of immature spermatozoa with extensive cytoplasmic retention, ultrastructural chromatin and midpiece abnormalities, and conglomerates containing sperm fragments were present more frequently in the semen of asthenozoospermic subjects with >4% of TUNEL-positive sperm cells. Low sperm motility seems to be accompanied by serious defects of gamete chromatin expressed as diminished sperm genomic integrity and abnormal DNA condensation and by defects of sperm midpiece. These abnormalities may reflect developmental failure during the spermatogenic remodeling process. The DNA fragmentation test may be considered as an additional assay for the evaluation of spermatozoa beside standard analysis and taken together with electron microscopy may help to determine the actual number of "healthy" spermatozoa thereby playing an important role during diagnosis and treatment of male infertility.

The objective of our study was to evaluate the incidence of spermatozoa with nuclear DNA strand breaks in patients with normal routine sperm parameters (26 subjects). Sperm DNA fragmentation was measured using TUNEL test assessed in flow cytometer. Variable percentages of sperm with damaged DNA (9.42 +/- 7.68%; range: 2-36) were found. Two categories of patients were distinguished: (1) patients (8 out of 26 subjects) with < or = 4% of TUNEL-positive sperm and (2) patients (18 out of 26 subjects) with > 4% of TUNEL-positive sperm. A significantly lower percentage of normal sperm forms was found in patients with > 4% of TUNEL-positive sperm than in patients with < or = 4% of TUNEL-positive sperm. Moreover, a significant negative correlation (r(s) = -0.50) was noted only between a proportion of normal sperm forms and a proportion of TUNEL-positive spermatozoa. In electron microscope, a large number of spermatozoa with immature chromatin was observed more frequently in subjects with > 4% of TUNEL-positive cells (11 out of 18 subjects). Our results suggest that in some patients with normal routine sperm parameters, DNA fragmentation may be associated with poor sperm morphology. The diminished sperm genomic integrity may result from molecular disturbances in nuclear remodeling process during spermiogenesis. TUNEL assay is a screening tool that may help to discriminate between fertile and infertile men and may help to predict successful in vitro fertilization.