PROJECT SUMMARY/ABSTRACT The overall objective of this study is to investigate the role of cilia in the fallopian tube (oviduct) in vivo. To accomplish this, my lab has developed a highly innovative, high resolution volumetric optical imaging method that provides unprecendented 4D resolution of the oviduct in its native state. Cilia are traditionally considered to generate the driving force required for oocyte/embryo transport, a theory reinforced by ciliopathy-associated infertility. While there are studies that identify muscular contractions as the predominant factor for transport, recent research conducted in mouse models with weakened ciliary beating demonstrated incomplete transport of ovulated oocytes, and as a result, the current consensus surrounding the control of tubal transport is divided. However, it is likely that a much more nuanced integration of cilia, contractions and flow is required for oocyte and embryo transfer. Using 4D in vivo imaging, our lab revealed a number of previously unknown activities of oocytes/embryos within the oviduct, suggesting that transport mechanisms are much more complex than originally thought. Pre-fertilization, oocytes in the upper ampulla are steered along the highly-ciliated luminal wall in a consistent circular pattern and their progression to the lower ampulla is controlled by a ‘gate-like’ luminal constriction. Furthermore, preimplantation embryos show fast, bi- directional movements in the muscular isthmus. This suggests that it is unlikely that the primary role of cilia is for directional movement of oocytes and embryos through the oviduct. Based on the preliminary studies in my lab, I believe that the current view of the role of cilia in the oviduct requires reassessment. The goal of the project is to determine if ciliary beating is necessary and sufficient for oocyte pick-up at the infundibulum, luminal steering in the ampulla, and the directional transfer of oocytes and embryos through oviductal regions. My lab is enriched with a unique blend of expertise in functional optical imaging and reproductive biology and as a result, we have developed a set of optical coherence tomography (OCT) methods which allow for: 1) live and dynamic volumetric imaging of mouse reproductive events with micro- scale spatial resolution; (2) depth-resolved mapping of cilia location and beat frequency; (3) quantification of the tubal contractile wave. These measurements are currently not possible with any other methods and they have never been applied in conjunction with genetic and pharmacological interventions before. Therefore, I have a rare opportunity to explore reproductive processes from a new and dynamic perspective. Successful completion of this project will lead to a deeper understanding of the exact contributions of ciliary beating and muscular contractions to oocyte and embryo transport in vivo, and provide valuable insights into the elusive workings of the oviduct. The proposed study will fill the ga...