Single cell RNA sequencing reveals fetal ovary development in Macaca fascicularis

The germ cells are vital for reproduction and heredity. However, the mechanisms for female germ cell development in primates, especially in late embryonic stage, has remained elusive. Here, we performed single-cell RNA sequencing of 12471 cells from fetal ovaries. We identified five cell types (germ cell, granulosa cell, theca cell, endothelial cell, macrophage cell), and explored the interactions between germ cells and niche cells. Interestingly, we demonstrated that two waves of oogenesis occur during fetal ovary development and ZGLP1 could activate oogenic program and is essential for meiosis initiation. Furthermore, late formed double strand breaks (DSBs) mediated by PRDM9 may lead to the apoptosis of germ cells during cyst breakdown process. Moreover, our study identified the origin of theca cells that may derive from Leydig cell like cells in fetal ovaries. Overall, our work provides new insights into the molecular and cellular basis of fetal ovary development at single-cell resolution. Single cell RNA sequencing on fetal ovary cells was performed from Macaca fascicularis.