Influence of seminal plasma on the chromatin stability of ejaculated human spermatozoa

Nuclear chromatin decondensation (NCD) of human ejaculated spermatozoa exposed to sodium dodecyl sulphate (SDS) has been studied. A high proportion of NCD reacting spermatozoa was only found in semen samples with a relatively low activity of some prostatic factor(s) (i.e. zinc/fructose ratio below 0.18) in the seminal plasma. Exposure to SDS for one h was found sufficient to reveal the main proportion of spermatozoa undergoing NCD in such a solution. Addition of seminal plasma with an apparently normal composition to a sperm population with a high NCD reactivity restored the sperm SDS resistance to normal, i.e. blocked the NCD-response. Other results indicated that NCD reactivity was decreased or abolished upon prolonged storage of the spermatozoa in the seminal plasma. The various results indicated that some factor(s) in the seminal plasma can preserve the nuclear chromatin stability of human spermatozoa and that this factor most likely is of prostatic origin.