(321) Spatiotemporal Dynamics of Ovulation Visualized in Live Mice

Kohei Umezu¹; Andre C. Faubert²; Shang Wang²; Richard R. Behringer³; Irina V. Larina¹ 

¹Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, USA

²Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA

³Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA


Abstract Text:

Ovulation is a dynamic multistep process that results in the release of an oocyte from the ovary for transport into the oviduct for fertilization. This process is a central event during the menstrual cycle, and ovulatory disorders are the primary cause of female infertility. Despite the essential role of ovulation in reproduction and its clinical importance, the real-time behaviors of oocytes, ovarian tissues, and oviducts during the ovulatory process in vivo are essentially unknown. In this study, we employed intravital, high-resolution, volumetric imaging to reveal the in vivo spatiotemporal dynamics of mouse ovulation and oviduct behaviors required for oocyte transport into the oviduct. Unexpectedly, we found that ovarian follicles opened in a controlled manner and slowly released the cumulus-oocyte complex (COC). Remarkably, oocytes were deformed as they squeezed through a relatively small opening of the follicle but regained a spherical shape shortly after being released. We also discovered repetitive pulses of fluid emitting from the oviduct that inflated the periovarian space, increasing fluid flow that was required for COC movement and subsequent active transport into the oviduct. In summary, our in vivo findings revealed novel cell, tissue, and organ behaviors during and after ovulation for oocyte movements to the site of fertilization. These studies identify previously unknown steps in ovulation and oocyte transport that if altered could result in female infertility.