New discoveries about the basic biology of the ovary may help researchers better understand the cause of ovarian disorders, including premature ovarian failure and polycystic ovary syndrome (PCOS), that can cause infertility in women, according to a press release from the National Institutes of Health.

Specifically, the researchers, whose findings in mice were recently published in Nature Communications, discovered the origin of theca progenitor cells — one of the cell types that make up the ovary — and how ovarian cells share information during development of an ovarian follicle.

Previously, in terms of the ovary, scientists were only aware of the origins of the egg and granulosa cells — another cell that surrounds the egg — but they lacked information on theca cells.

“The answer to this question remained unanswered for decades, but using a technique called lineage tracing, we determined that theca cells in mice come from both inside and outside the ovary, from embryonic tissue called mesenchyme,” Humphrey Yao, PhD, corresponding author of the study and a researcher at the National Institute of Environmental Health Sciences, said in the release.

“We don’t know why theca cells have two sources, but it tells us something important — a single cell type may actually be made up of different groups of cells.”

Yao also explained that women cannot produce the hormones that sustain follicle growth, one of which is androgen, without theca cells. The granulosa cells, Yao noted, convert androgen to estrogen.

In their study, the researchers identified the molecular signaling system that allows theca cells to produce androgen. The communication pathway is derived from granulosa cells and the oocyte. This interaction between the oocyte, granulosa cells and theca cells could shed some light on the development of ovarian disorders.

“The problem starts within the theca cell compartment,” Chang Liu, PhD, a visiting fellow in Yao’s research group and first author on the paper, said in the release. “Now that we know what makes these cells grow, we can search for possible genetic mutations or environmental factors that affect the process leading to ovarian cell disorders.”

In the future, Yao would like to evaluate the two cell types that comprise theca cells, as well as examine whether their findings in mice will be the same for humans. This work may help identify how theca cells affect fertility in women, according to the release.

Reference

  1. Liu C et al. Nat Commun. 2015;doi:10.1038/ncomms7934.