A systematic review of the factors affecting sperm binding and release from the oviduct using in vitro experimental animal models

After insemination, spermatozoa bind to epithelial cells of the isthmic part of the oviduct to form a functional sperm reservoir responsible for regulating sperm viability and capacitation before the ovulation signal that triggers its release. Understanding this information is essential to optimizing in vitro fertilization (IVF) protocols and contributing to the efforts to develop treatment for infertility resulting from fertilization failure. This review aims to provide a comprehensive and systematic assessment of the literature on the non-steroid hormone factors involved in sperm binding and release from the sperm reservoir in animal species using in vitro experiments. PubMed, Web of Science, and Google Scholar databases were searched, and eligible studies included articles published between 1 st January 1990 and 31 st July 2024 reporting factors involved in sperm binding and release from the oviduct, and this could be used to optimize IVF systems and treatment of fertilization failure-related infertility. Studies that co-cultured sperm and oviductal explants or oviductal epithelial cells from bovine, porcine, canine, camelid, equine, hamster, and ovine were used, and different culture systems were evaluated in this study. Overall, sperm binding to and from the oviductal epithelial cells was influenced by several factors, such as carbohydrates and their derivatives, seminal plasma proteins, glycoproteins, tyrosine phosphorylation of sperm, endocannabinoids, sex-sorting, and glycosaminoglycans. These factors either promoted or inhibited the binding sperm binding to and from oviductal cells. We therefore postulate that these non-steroid factors are potential candidates that can be used to optimize IVF outcomes in both human and animal species.