The continued absence of functional germline stem cells in adult ovaries.

Ovaries are central to development, fertility, and reproduction in women. A particularly interesting feature of ovaries is their accelerated ageing compared to other tissues, leading to loss of function far before other organs senesce. The limited pool of ovarian follicles is generated before birth and once exhausted, menopause will inevitably commence around the age of 50 years marking the end of fertility. Yet, there are reports suggesting the presence of germline stem cells and neo-oogenesis in adult human ovaries. These observations have fueled a long debate, created experimental fertility treatments, and opened business opportunities. Our recent analysis of cell types in ovarian cortex of women in fertile age could not find evidence of germline stem cells. Like before, our work has been met with critique suggesting methodological shortcomings. We agree that excellence starts with methods, and welcome discussion on pros and cons of different protocols. In this commentary, we discuss the recent re-interpretation of our work.