When do Oocytes Begin to Experience the Effects of Age?

Oocytes have a unique journey. Present in a woman's ovaries from before birth, they can lie dormant for up to five decades. They usually awaken from dormancy during reproductive years, undergoing a rapid-fire process of maturation where the cells grow 64 times their size, which in turn leads to ovulation and sometimes fertilisation.

It is well known that fertility declines with age, and poor oocyte quality accounts for the majority of female fertility problems. A longstanding question in reproductive biology is pinpointing the origin of these age-associated defects.

Early-stage oocytes are exposed to decades worth of biological and environmental factors which could make them vulnerable to cumulative damage. At the same time, the rapid growth phases associated with the maturation of oocytes could be introducing errors from exposure to harmful agents or lifestyle factors.

Are both factors at work, or is one more important than other? By understanding the basic mechanisms at work, researchers can help predict whether interventions designed to improve oocyte quality could work and design new, more effective ones.

Dr. Elvan Böke, Group Leader at the Centre for Genomic Regulation in Barcelona, will explore this question thanks to a new project funded by the Global Consortium for Reproductive Longevity & Equality (GCRLE) at the Buck Institute for Research on Aging, made possible by the Bia-Echo Foundation. Dr. Böke will receive $200,000 dollars over a two-year period.

“This project aims to understand fundamental aspects of oocyte development which might help address unexplained infertility, which accounts for around one in four cases of infertility," says Dr. Böke. "The backing of the GCLRE is a pivotal step towards enhancing our understanding of female reproductive health,” she adds.

The project is part of Dr. Böke’s wider research efforts in exploring oocyte biology. She has previously demonstrated that oocytes can remain ‘on standby’ for decades by skipping a fundamental metabolic reaction thought to be used by all types of cells. This knowledge could be used to test new interventions.

Studying how oocyte quality declines with age is critical for addressing the demographic emergencies resulting from more people choosing to have children later in life. Many countries are experiencing fewer births, which, when combined with an aging population, can pose challenges for a country's economy and social support systems.

Despite this challenge, fundamental knowledge on reproduction remains underfunded. According to the GCLRE, despite affecting half the world's population, women’s health receives less than 1% of research funds. Only a fraction of that 1% has been applied to study reproductive longevity. The GCLRE has awarded $7.1 million in this call to a total of 28 scientists around the world.

Image: Image of human oocyte. Credit: Aida Rodriguez/Center for Genomic Regulation