The Transformative Impact of Extracellular Vesicles on Developing Sperm
Objective To review the role of extracellular vesicles (EVs) released from the male reproductive tract and their impact on developing sperm. We discuss how sperm exiting the seminiferous tubules, although developmentally mature, require further modification. Acquisition of various functions including increased motility, transfer of cargoes and ability to undertake the acrosome reaction are mediated through the interaction between sperm and EVs. Methods A review of the literature identified that EVs are released from different portions of the male reproductive tract, notably the epididymis and prostate. These EVs interact with sperm as they pass from the seminiferous tubules to the epididymis and vas deferens prior to ejaculation. Results EVs are small lipid bound particles carrying bespoke RNA, protein and lipid cargoes. These cargoes are loaded based on the state of the parent cell and are used to communicate with recipient cells. In sperm, these cargoes are essential for post testicular modification. Sperm extracted from the proximal epididymis are poorly motile and unable to carry out the acrosome reaction. Conclusions Interaction between developing sperm and EVs is important for the subsequent function of sperm. Little is known however about EVs released from the seminiferous tubules to developing sperm or in the fetal and pre-pubertal testes. A greater understanding, especially in the formation and development of the spermatogonial stem cell niche may lead to new insights as to how damage to this niche may be prevented and preserve future fertility.