Biological clock governs female fertility

Researchers have identified the biological clock that governs female fertility, paving the way for medical approaches to treating infertility in women.
Some women can have successful pregnancies at the age of 50, whereas other are unable to get pregnant when they are 30.
Researchers are not yet able to fully explain such differences.
One factor is that the onset of menopause is influenced by the point at which the uterus runs out of eggs to release.
The study at the University of Gothenburg in Sweden sheds light on the mystery of the biological clock that governs fertility.
Just as newborn infants require nurturance in order to survive, eggs in the uterus need nourishment and support from the granulosa cells of the primary follicle.

According to the latest discovery by Professor Kui Liu's research team, a signalling pathway in these cells plays a key role in enabling immature eggs to survive.

The mTOR signalling pathway in the granulosa cells is necessary for activating expression of the kit ligand growth factor, which subsequently binds to the c-kit receptors of eggs and determines their fate.
"This mechanism permits the granulosa cells to decide when eggs will begin to grow and when they will die. In that sense, they serve as a kind of biological clock that monitors the onset of menopause," said Liu, who is affiliated with the Department of Chemistry and Molecular Biology at Gothenburg.

Researchers believe that the discovery will point the way to interventions that stimulate the growth of eggs that have been unable to mature.
Their hope is that increased knowledge about the molecular mechanisms that govern development in human eggs can be applied to clinical treatment of female infertility in the years to come.