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This investigation was conducted to evaluate the interaction among semen characteristics, endocrine profiles, and testicular biopsies in 968 infertile men. Men were divided into five groups according to age. Sperm with abnormal morphology and percentage of progressive motility were found in patients over 40 years of age. However, there was a remarkable heterogeneity of semen characteristics within the examined groups. Azoospermia was present in 43 patients (4%), oligozoospermia in 73 (7%), and polyzoospermia in 126 (13%). Sexually transmitted disease was found in 28%. It would appear that age contributed to the decline in semen quality in men over 40 years old.
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Merino et al. (1995) studied this question.
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