A team of scientists at the National Institutes of Health has solved a mystery about the origin of a specific cell type that makes up the ovary, according to a study in the journal, Nature Communications, published online in April.
Researchers discovered how ovarian cells share information during development of an ovarian follicle, which holds the maturing egg, and they believe the findings will help them better understand ovarian disorder causes, such as premature ovarian failure and polycystic ovarian syndrome, which result in hormone imbalances and infertility.
The ovarian follicle, the basic functional unit of the ovary which contains the egg, is surrounded by two distinct cell types — granulosa and theca cells. Researcher and author Humphrey Yao, PhD, and his team found that the three components — the egg, granulosa cells and theca cells — must communicate to maintain a healthy follicle, according to a news release. The origin of the theca cell was unknown prior to the study, Yao said.
“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,” Yao 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.”
Theca cells help produce hormones that sustain follicle growth. One of those hormones is androgen, widely thought to be a male hormone. When studied, granulosa cells convert androgen to estrogen, researchers learned.
According to the release, scientists uncovered the molecular signaling system that enables theca cells to make androgen, a communication pathway that is derived from granulosa cells and oocyte, the immature egg cell. Communication between the egg, granulosa and theca cells was an unexpected finding and may give insight into how ovarian disorders arise.
“The problem starts within the theca cell compartment,” Chang Liu, PhD, a visiting fellow in Yao’s 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.”
More research on theca cells will be conducted in the future, the researchers said, and may reveal the roles theca cells play in female fertility.
“Our studies provide the first genetic evidence for the origins of theca cells and reveal a multicellular interaction critical for the formation of a functional theca,” researchers stated in the study.