Free amino acids in semen: measurement and significance in normal and oligozoospermic men.

Measurement of free amino acids in seminal plasma from fertile and infertile oligozoospermic subjects revealed a quantitative reduction of these molecules in infertile patients. Study of the effect of acidic media on seminal plasma appears to suggest the primary role of free amino acids in the "protection" of spermatozoa in the vagina, and the failure of sperm progression in the female genital tract may be due to a decrease of these molecules in semen of infertile patients.