Localization of single-stranded DNA in human sperm nuclei.

OBJECTIVE

To localize foci of single-stranded (ss) DNA in sperm nuclei of fertile and infertile men.

DESIGN

Prospective, observational study.

SETTING

University infertility clinic.

PATIENT(S): Semen samples from 12 consecutive asthenoteratospermic men presenting for infertility evaluation and 5 consecutive fertile men presenting for vasectomy.

INTERVENTION(S): Semen analysis, semen processing, and immunocytochemistry using an antibody targeting ssDNA.

MAIN OUTCOME MEASURE(S): Sperm nuclear ssDNA immunostaining pattern in whole and processed semen samples.

RESULT(S): Immunocytochemistry (using ssDNA antibody) demonstrated one of two sperm nuclear staining patterns: [1] faint punctated staining, and [2] diffuse nuclear staining. Infertile men had a higher proportion of spermatozoa exhibiting diffuse ssDNA staining than did fertile men (52 +/- 19 vs. 14 +/- 13, respectively). The proportion of spermatozoa exhibiting diffuse ssDNA staining was significantly higher in whole compared with processed semen. Positive (DNAse-treated nuclei) and negative controls (S1 nuclease-treated nuclei) were obtained to validate the specificity of the antibody.

CONCLUSION(S): Human sperm nuclei generally exhibit discrete (presumably peripheral) foci of ssDNA. The data also show that infertile men have a higher proportion of sperm nuclei with diffuse areas of ssDNA than do fertile men, and suggest that spermatozoa with diffuse nuclear staining are abnormal.