A quiet space during rush hour: Quiescence in primordial germ cells.

Quiescence is a common character in stem cells. Low cellular activity in these cells may function to minimize the potential damaging effects of oxidative stress, reduce the number of cells needed for tissue replenishment, and as a consequence, perhaps occupy unique niches. Quiescent stem cells are found in many adult human tissues, the hematopoietic stem cells are paradigmatic, and more recently it appears that stem cell of the germ line in many animals display quiescence characters. Here we explore the diversity of quiescence phenotypes in primordial germ cells, leveraging the diverse mechanisms of germ cell formation to extract evolutionary significance to common processes.