RESUMEN
OBJECTIVE: To investigate the frequency of round-headed, or acrosomeless, spermatozoa, determine the percentage and evaluate the possible correlation with other semen parameters. STUDY DESIGN: Semen specimens from 114 subfertile men aged 24-53 years (mean +/- SD 33.3 +/- 6.3) and from 60 fertile men aged 24-44 years (33.1 +/- 4.2) were studied. Two semen specimens were examined from each individual, with a six- to eight-week interval. Sperm morphology was evaluated from Papanicolaou-stained smears, and the classification of abnormal sperm forms was made according to WHO guidelines. RESULTS: The percentage of round-headed spermatozoa was 2.3% +/- 0.5 in subfertile and 0.5% +/- 0.1 in fertile men. Round-headed spermatozoa existed in semen specimens from 36.8% of subfertile and 25.0% fertile men. Of subfertile men, 14.9% had round-headed spermatozoa at a higher percentage than the highest normal limit found in sperm smears from fertile men. CONCLUSION: In some subfertile men with a high percentage of round-headed spermatozoa, infertility could be attributed to the cause of this morphologic abnormality. Moreover, morphologic abnormalities in the neck were significantly more frequent in round-headed spermatozoa than in spermatozoa with normal heads.