Abstract
A substance with TPA immunoreactivity is present in human seminal plasma. This seminal plasma TPA shows immunological similarity with TPA isolated from a pool of carcinoma tumors. TPA is taken up by live spermatozoa and it cannot be easily washed out. Split-ejaculate studies suggest that TPA originates mainly from the prostate. TPA is not correlated with the spermatozoa count, total number of spermatozoa, percentage of normal spermatozoa, or forward motility. The mean seminal plasma concentration of TPA in morphologically normal ejaculates is 14,531 U/liter. No difference was found in the TPA levels between the normal group and various groups of patients under investigation for involuntary infertility.