Luminal uterine epithelia cells (UECs) have a surge in vesicular activity during early uterine receptivity. Recent studies have highlighted the importance of uterine extracellular vesicles (EVs) in maternal-foetal communication in a number of species including humans. These vesicles are thought to exit the UECs via exocytosis transport mechanisms. Exocytosis mechanisms in UECs during uterine receptivity were investigated with transmission electron microscopy (TEM) and via localisation and quantification of various SNARE proteins involved in exocytosis (VAMP2, syntaxin 2, 3 and SNAP23). All SNARE proteins investigated were found in the apical cytoplasm of UECs at the time of receptivity and exhibited significantly higher abundance at this time compared to the time of fertilisation. Interestingly, SNAP23 was identified in the luminal fluid exclusively at the time of uterine receptivity. TEM examination further localised a variety of EVs in the uterine luminal space at the time of receptivity. Porosomes, a plasma membrane ultrastructure involved in “kiss and run” exocytosis, were found to be significantly increased at receptivity using quantitative TEM analysis. Overall, this study found at an ultrastructural level there is an increase in vesicular activity via EVs and porosomes at the time of receptivity. Our morphological and protein results suggest that exocytosis occurs predominantly at the time of receptivity in the rat utilising a variety of different exocytosis routes. This work has also shown that this increase in exocytosis is controlled by SNARE proteins, which are therefore responsible for creating the utmost microenvironment for blastocyst implantation. In particular, the presence of SNAP23 in the luminal fluid exclusively at the time of receptivity has immense potential for use as a receptivity marker, which could be used to improve artificial reproductive technologies and our understanding of uterine receptivity during early pregnancy.