Relevance of zinc in human sperm flagella and its relation to motility

Objective: To measure the zinc content of human sperm flagella and to analyze its relation to sperm motility. Design: Prospective study. Setting: Center of Dermatology and Andrology. Patient(s): Semen samples collected from 90 andrology patients and healthy donors after 3–5 days of sexual abstinence. Intervention(s): None. Main Outcome Measure(s): Sperm morphology after Shorr staining, sperm motility, and patient age were recorded. In addition, zinc concentrations in the seminal plasma, sperm heads, and flagella were determined with the use of atomic absorption spectrometry. Result(s): The mean zinc concentration was 144.3 mg/L in the seminal plasma and 146.9 mg/L in the whole ejaculate and was significantly correlated with parameters of motility. The sperm heads contained only 6.7% of the zinc that was present in the whole spermatozoon. The zinc concentration in the flagella was negatively correlated with sperm motility and velocity. In addition, it was positively correlated with the percentage of abnormally blue-stained flagella and the age of the patients. Conclusion(s): Our results clearly demonstrate the importance of zinc elimination during epididymal sperm maturation for functional competence of the outer dense fibers and, therefore, generation of motility.