The Explosion of Life: Lessons from Live Imaging of Ovulation

Ovulation is the process by which an egg is released from an ovarian follicle, ready for fertilisation. It is a multi-scale transformation that converts endocrine cues into coordinated tissue and extracellular matrix remodelling, culminating in physical rupture of the follicle wall. Live imaging has reshaped understanding by replacing static snapshots with direct observation of sequence and timing. Here, we outline the architecture of the preovulatory follicle and the LH-driven signalling programmes that coordinate cumulus expansion, oocyte maturation, tissue remodelling and rupture. We then chart key imaging milestones-from early time-lapse of exteriorised ovaries, to clinical endoscopy in humans, perfused ovary preparations, intravital multiphoton microscopy, and ex vivo live imaging of isolated follicles. Finally, we summarise emerging approaches to probe physical regulation, including intrafollicular pressure measurements and complementary methods to quantify tissue and matrix mechanics. Together, these advances show that ovulation is a staged programme that demands quantitative, time-resolved measurements.