Rapid post-ejaculatory inhibitory effect of seminal plasma on sperm nuclear chromatin decondensation ability in man

The stability of the nuclear chromatin in human spermatozoa soon after ejaculation was studied by exposing the cells to sodium dodecyl sulphate (SDS) one to 20 min after ejaculation. Semen samples were obtained both from men with apparently normal, and from men with impaired prostatic secretion (= subnormal seminal plasma [Zn]). The sperm nuclear resistance to decondensation in SDS increased in both groups during the first 15 min after ejaculation, but was significantly lower in the semen samples with subnormal [Zn]. This fast post-ejaculatory increment in sperm SDS resistance was significantly reduced by a 5-fold saline dilution of the semen at the time of ejaculation. It is discussed if the observed stabilization with time was illusory and that a prostatic component instead counteracted an intrinsic nuclear chromatin decondensation (NCD) process initiated by SDS derangement of spermatozoal membranes.