New research just published in the journal Reproduction shows that fibrosis in the ovaries may be a major cause of age-related infertility. Past research has tended to focus on the eggs, not the environment where they develop. These new findings may lead to better treatments for infertility and other reproductive problems.
A research team examined the ovaries of two groups of mice. One group consisted of younger reproductive-aged mice. The other group consisted of older mice that were still able to reproduce. The second group was equivalent to women ages 38-45. The team stained tissue and examined the ovaries using epifluorescence, confocal, and polarized light microscopy.
The researchers found that most of the older mice had signs of fibrosis, including ovarian scarring. In some cases, up to 35% of the ovarian tissue was fibrotic. The team also noticed the presence of multinucleated macrophage giant cells, a type of immune cell, in the older mice. When found in tissue, multinucleated macrophage giant cells tend to cause chronic inflammation. The older group of mice also had increased expression of genes associated with tissue inflammation.
The results of the study show that age-related reproductive issues may be related to the ovarian environment. Ovarian tissue in older mice was inflamed and fibrotic. Since the eggs develop in the ovaries, ovarian problems could lead to lower quality egg production. Past research has generally focused on the eggs; this was the first study to look at the environment where they develop.
The researchers hope that their findings will lead to improved fertility treatments. If we can fully understand the effects of aging on the ovaries, we may be able to prevent or reverse the process. Understanding ovarian fibrosis could also help with the treatment of polycystic ovary syndrome, a common endocrine disorder that affects over 200,000 Americans each year.
Shawn M Briley et al. Reproductive age-associated fibrosis in the stroma of the mammalian ovary. Reproduction (2016).