To date, all the research involving ovulation samples is done on fixed tissues, which means that only temporal stages of this process are captured. Although such analyses are valuable, they are not very helpful when the object of study is as fluid as ovulation. The oocytes are primary ova in the ovarian follicles stages.
The technical report, “Ex vivo imaging reveals the spatiotemporal control of ovulation,” published in Nature Cell Biology, shows how researchers used a new image capture method to identify three distinct phases of ovulation: follicle growth, shedding and rupture that results in the discharge of an egg.
Both confocal and two-photon microscopy was used to capture the images of live, isolated mouse ovarian follicles. Four types of composite mouse transgenic donors encompassing expression markers for cell membranes and DNA enabled the visualisation of complex movements.
The technique entailed imaging at 10 minutes intervals over 24 hrs ensuring detailed observation of ovulation at both the cellular level and the whole follicle. As a next step to the latter, the team did inhibition testing to support the identification of causal relations after the first observation and data collection phase.
The first phase which was detected was the follicle extension where hyaluronic acid was released to foster the uptake of fluids to fill the follicle which as a result enhanced its enlargement. Earlier rises were followed by inhibition tests of hyaluronic acid synthesis With decreased cell proliferation and ovulation blockage, the direct impact was proven.
Last of all, follicle rupture, then shedding of the follicular fluid, cumulus cells and the egg ensued. Rupture and egg release were seen to occur in three steps: Angiopathic changes such as; fluid, cellular rupture and egg release.
Other processes that were identified to be involved in the process include molecular mechanisms that control mitochondrial energy production and actomyosin contractility. 6-9 h after stimulating the first wave of ovulation, the molecular abnormalities of the changes in the expression of the pathways that reflect the increased energy demand of smooth muscle cells during contraction were identified.
Disruption of mitochondrial function diminished contraction and blocked ovulation and showed its dependency on mitochondrial ATP synthesis.
This new approach not only reveals the finer details in the space time dynamics of ovulation and offers new ways of exploring how the consequently cellular and molecular mechanisms are coupled in reproduction but offers a simply fascinating video of nature in action.
Reference:
Jackson J. Live imaging of ovulation in action reveals three distinct phases. Physics
