Physiological functions of seminal vesicle secretions in male fertility

In many mammals, accessory gland secretions are ejaculated into the female reproductive tract, along with sperm, and the prostates and seminal vesicles are the main glands responsible for these secretions. Cauda epididymal sperm can efficiently fertilize eggs in vitro; however, we found that seminal vesicle secretions improved sperm fertilization rates in vivo by artificial insemination. Furthermore, using the seminal vesicle-removed mice, other studies have shown that seminal vesicle secretions contribute to embryogenesis and offspring health by regulating the environment in the female reproductive tract. These results indicate the significance of accessory gland secretions in fertilization and development in vivo. More than 700 proteins are present in the accessory glands, and genome editing accelerates the functional analysis of these proteins at the individual level. For example, some studies reported results from phenotypic analyses of genetically modified mice that were different from those of in vitro experiments. In this review, we discuss the current findings on the effects of accessory gland secretions on male fertility and the future prospects.