17β-Estradiol induces supernumerary primordial germ cells in embryos of the polychaete Platynereis dumerilii.

In the polychaete Platynereis dumerilii exactly four primordial germ cells (PGCs) arise in early development and are subject to a transient mitotic arrest until the animals enter gametogenesis. In order to unravel the mechanisms controlling the number of PGCs in Platynereis, we tested whether the steroid 17β-estradiol (E2) is able to induce PGC proliferation, as it had been described in other species. Our data provide strong support for such a mechanism, showing that E2 significantly increases the occurrence of larvae with supernumerary PGCs in Platynereis in a dose dependent manner.

Hidden in the crowd: primordial germ cells and somatic stem cells in the mesodermal posterior growth zone of the polychaete Platynereis dumerillii are two distinct cell populations.

Background: In the polychaete Platynereis, the primordial germ cells (PGCs) emerge from the vasa, piwi, and PL10 expressing mesodermal posterior growth zone (MPGZ) at the end of larval development, suggesting a post-embryonic formation from stem cells.

Methods: In order to verify this hypothesis, embryos and larvae were pulse labeled with the proliferation marker 5-ethynyl-2'-deoxyuridine (EdU) at different stages of development. Subsequently, the PGCs were visualized in 7-day-old young worms using antibodies against the Vasa protein.