Ovarian Organoids-derived Cells Are Not Oogonial Stem Cells In Spite of Expressing Germ Line Markers

The opinion that female mammals have lost the capacity for oocyte production after birth has been challenged recently by the discovery of proliferative germ cells or oogonial stem cells (OSCs) in adult mouse and human ovaries. However, the existence of OSCs in postnatal mammalian ovaries is still a subject of debate. Here, we hypothesized that mimicking the ovarian microenvironment in vitro using cutting edge organoid model of ovary would provide a suitable environment for the isolation presumptive OSCs from adult mouse and human ovaries. We developed ovarian organoids that provided a permissive niche for derivation of germ cell like cells that expressed germ line markers and differentiated to produce oocyte like cells both in vivo and in vitro and contributed to new offspring following injection to mouse ovary. However, analysis the data obtained from RNA-Sequencing revealed the immune cells (monocyte) characteristics for these ovarian organoids-derived gem cell (ODGCs) like cells and not OSCs. Re-analysis of offspring genome with new primer that identifies IRES-GFP confirmed lack of GFP in their genome. Therefore, our study does not support the existence of OSCs in mouse neither human ovaries.