“…The opinion that seminal plasma is not just a transport medium for the transfer of spermatozoa to the maternal tract is not recent, and its immunomodulatory properties in protecting spermatozoa, priming the uterus for pregnancy and modulating killer cell activities have long been recognized (Koch & Ellendorff 1985, Rees et al 1986, Saxena et al 1988, Cardoso et al 1993, Liang et al 1993. In the mouse, mating induces a marked, yet transient, inflammatory response associated with endometrial leukocyte infiltration, which commonly dissipates by the time of blastocyst hatching and implantation (Robertson et al 1997).…”