Extracellular Vesicles in Reproduction: Biology, Production, and Potential Applications in Livestock Breeding.

Extracellular Vesicles (EVs) are small, membrane-bound particles released by cells into biological fluids, where they function as mediators of intercellular communication. These vesicles transport a diverse array of bioactive molecules, including proteins, lipids, and nucleic acids, and play essential roles in regulating physiological and pathological processes. Recent research has revealed the significance of EVs in reproductive biology, particularly in the areas of spermatozoa maturation, oocyte development, embryo implantation, and maternal-fetal interactions. Given their widespread distribution and biological importance, EVs have been increasingly studied for their potential applications in both human and livestock reproductive medicine. Understanding the mechanisms by which EVs contribute to reproductive processes is crucial, as they offer novel opportunities for improving reproductive health, diagnosing fertility disorders, and enhancing assisted reproductive technologies. In males, EVs derived from seminal plasma and the epididymis influence sperm motility, capacitation, and fertilisation potential. In females, vesicles secreted within follicular, oviductal, and uterine fluids mediate communication between the oocyte, embryo, and maternal reproductive tract. Furthermore, placental-derived EVs regulate immune tolerance, vascular remodelling, and fetal development throughout pregnancy. EVs are emerging as promising tools for fertility assessment and reproductive diagnostics. Their molecular cargo reflects the physiological state of the reproductive system, enabling their use as non-invasive biomarkers for evaluating gamete quality, embryo viability, and pregnancy health. Despite their immense potential, challenges remain in optimising EV isolation, improving characterisation techniques, and deciphering the precise molecular mechanisms underlying their function. Standardisation of methodologies, development of targeted vesicle-based therapeutics, and validation of their efficacy in reproductive medicine are necessary to fully realise their clinical utility. The field of EV research in reproductive biology continues to evolve rapidly, and ongoing studies will undoubtedly lead to new insights into their role in fertility, embryo development, and pregnancy maintenance.