Decreasing ability among women to produce healthy eggs as they become old may be due to excessive scarring and inflammation in their ovaries, reports a new study. In this study, published in the journal Reproduction, scientists examined the reproductive age-related changes that occur in the environment in which the eggs develop, known as the ovarian stroma and shows how the ageing of ovarian environment affects the quality of eggs it produces.
“Under the microscope, eggs from reproductively young and old animals may look identical, but the environment in which they are growing is completely different. Ovaries from reproductively old mice are fibrotic and inflamed. Environment impacts the growth of eggs and leads to decrease in quality,” said Francesca Duncan, researcher, Northwestern University Feinberg School of Medicine.
In this study, researchers analysed ovarian tissue from populations of reproductively ‘young’ (equivalent to women in their early twenties) and ‘old’ mice (equivalent to women ages 38-45). They consistently identified fibrosis in the reproductively ‘old’ mice. This age period is associated with a decline in reproductive function and egg quality in both humans and mice. Ovarian fibrosis is a key feature of polycystic ovary syndrome, a common endocrine system disorder among women of reproductive age.
Researchers also found a type of immune cell (multinucleated macrophage giant cells) in the ovaries of reproductively ‘old’ mice only. When found in other tissues, these cells are associated with chronic inflammation. They also found ovaries from mice of advanced reproductive age expressed genes and produced proteins that are highly inflammatory.
“Our work establishes fibrosis and inflammation as hallmarks of the ageing ovary and lays the foundation for considering the use of anti-fibrotic or anti-inflammatory treatments to delay or counteract the impact of reproductive ageing,” added Duncan. These findings could result in new treatments that preserve fertility by delaying ovarian aging.