Ageing is a condition characterised by the accumulation of physiological defects in organisms as they grow older. Reproductive ageing is of particular concern to humans, as older women may struggle with infertility. To better understand the processes underlying reproductive ageing, Zuzana Kocsisova, Kerry Kornfeld and Tim Schedl characterise cellular changes in the germline of ageing C. elegans hermaphrodites. They notice population-wide decreases in the size of both the germline and progenitor zone, and occasional instances of endomitotic oocytes, which display abnormal masses of chromatin. Furthermore, the mitotic cell cycle in the progenitor zone is slowed, which coincides with a lower rate of meiotic entry upon exit from the progenitor zone in older adults. The authors also observe that the two Notch effectors SYGL-1 and LST-1 are present in a lower number of germline cells, suggesting a decline in Notch signalling, which is normally required to maintain the undifferentiated state of cells in the progenitor zone. Therefore, they propose that decreased Notch signalling reduces the pool of undifferentiated germ line cells, thus affecting the worms’ ability to sustain the level of progeny production seen in younger adults. Together, these results provide new insight into the age-induced changes within germ cells and hint at the mechanisms underlying them.
