The role of the oviduct and extracellular vesicles during early embryo development in bovine

Abstract

The oviduct is an important reproductive structure that connects the ovary to the uterus and takes place to important events such as oocyte final maturation, fertilization and early embryonic development. Thus, gametes and embryo can be directly influenced by the oviductal microenvironment composed by epithelial cells such secretory and ciliated cells and oviductal fluid. The oviduct composition is anatomically dynamic and is under ovarian hormones control. The oviductal fluid provides protection, nourishment and transport to gametes and embryo and allows interaction to oviductal epithelial cells. All these functions together allows the oviduct to provides the ideal environment to the early reproductive events. Extracellular vesicles (EVs) are biological nanoparticles that mediates cell communication and are present at oviductal fluid and plays an important role in gametes/embryo - oviductal cells communication. This review will present the ability of the oviducts based on its dynamic and systemic changes during reproductive events, as well as the contribution of EVs in this process.

Keywords: cell communication; oviductal environment; oviductal fluid.

Figure 1. Reproductive events occurring in the oviduct mediated by extracellular vesicles. Schematic representation of female reproductive tract in post ovulation stage of estrus cycle and oviductal anatomic regions. The infundibulum is responsible for capturing recently ovulated cumulus oocyte complexes (COC). (I)The ampullary region is mainly composed by secretory epithelial cells which allows a high production of oviductal fluid which is also composed by follicular fluid. (a) Together these vesicles act at the oocyte final maturation; (b) At the ampulla region cumulus oocyte complexes and sperm will meet, and subsequently initiates the fertilization process. (II) The isthmic region is mainly composed by ciliated cells; (c) Once the fertilization happened, the initial embryo development occurs; (d) The embryo develops, activates its genome and modulates the isthmic region mediated by embryo and oviductal extracellular vesicles. This figure was Created with BioRender.com.