Seminal fluid effects on female reproductive function in laboratory, livestock, and domestic species

When seminal fluid is delivered into the female reproductive tract by natural mating or artificial insemination, seminal fluid components elicit biological responses from female tract cells and tissues. This "male to female seminal fluid signaling" affects the chances of conception and pregnancy, depending on the balance of signals in the seminal fluid - which can vary in relation to the genetics and physiological state of individual males. Seminal plasma is instrumental in eliciting female responses, and sperm also contribute. Signaling agents include cytokines and prostaglandins synthesized in the seminal vesicles and other male accessory glands, delivered to the female tract in soluble form, as cargo of seminal extracellular vesicles, or in association with sperm. These agents modulate oviduct and endometrium secretions, and activate immune cell recruitment and gene expression changes in female reproductive tissues, that in turn initiate an adaptive immune response to semen and the conceptus. Collectively these effects can exert either permissive or inhibitory consequences for conception, embryo development, and receptivity to implantation. Extensive studies show seminal fluid effects in porcine, equine, bovine, ovine and canine species, with variations between species due to the site of seminal fluid deposition and female reproductive tract anatomy. Greater insight into the biological function and molecular basis of seminal fluid effects in females has potential applications in novel treatments and management practices to support optimal reproductive outcomes in domestic, livestock and endangered animal species.