From adhesion to communication: how sperm binding modulates the bovine oviductal microenvironment†

Fertility in mammals is influenced by the interaction between spermatozoa and the female reproductive tract. While sperm has traditionally been regarded as passive carriers of paternal DNA, there is growing evidence that they actively influence the oviductal environment. In cattle and other species, a subpopulation of sperm binds to epithelial cells in the isthmus, forming a reservoir that prolongs viability, modulates capacitation, and ensures a timed release of competent cells. This adhesion involves multiple mechanisms, including recognition of specific glycans such as fucosylated residues, protein-protein interactions, and binding between integrins and fibronectin. Beyond mechanical anchoring, these contacts initiate signaling cascades within the epithelium. Ciliated cells transmit signals to secretory cells, leading to transcriptomic remodeling and changes in protein and extracellular vesicle secretion. As a result, the luminal fluid becomes enriched with cytokines, antioxidants, and immunomodulatory factors that help maintain sperm function under oxidative and immune pressure. Interestingly, the oviduct also appears capable of discriminating between spermatozoa of different quality or those subject to sexing procedures, although the precise molecular mediators remain poorly defined. This selective response suggests that sperm interact with maternal regulatory mechanisms and may represent one of several contributors to oviductal plasticity, together with endocrine, oocyte- and embryo-derived signals. From an applied perspective, a deeper understanding of these mechanisms may help to refine assisted reproductive technologies, by improving in vitro fertilization media or developing functional assays for sire fertility. Despite recent progress, much remains to be clarified regarding how sperm-derived signals are sensed and integrated by the oviduct.