Microscale pressure measurements and optical coherence tomography reveal time-dependent biomechanical stages of ovulation in mice

During ovulation, antral follicles undergo coordinated remodeling that results in egg release and corpora lutea formation, which are key processes for fertility and endocrine function. Using an <i>ex vivo</i> murine ovulation model integrated with time-lapse imaging, microscale pressure sensing, and optical coherence tomography (OCT), we characterized and quantified the sequence of mechanical events driving follicle rupture. We demonstrated that ovulation begins with a hyaluronan-dependent rise in intrafollicular pressure, followed by antral expansion and thinning of the follicle wall, which leads to elevated wall stress preceding rupture. Additionally, we characterized changes in ovulatory biomechanical dynamics associated with advanced reproductive age. By mapping the physical timeline of ovulation, this work establishes a framework for understanding the biomechanical regulation of egg release and provides insight into how age-related changes in follicular biomechanics may contribute to infertility.