Intercellular bridges coordinate the transition from pluripotency to meiosis in mouse fetal oocytes.

Abstract

Meiosis is critical to generating oocytes and ensuring female fertility; however, the mechanisms regulating the switch from mitotic primordial germ cells to meiotic germ cells are poorly understood. Here, we implicate intercellular bridges (ICBs) in this state transition. We used three-dimensional in toto imaging to map meiotic initiation in the mouse fetal ovary and revealed a radial geometry of this transition that precedes the established anterior-posterior wave. Our studies reveal that appropriate timing of meiotic entry across the ovary and coordination of mitotic-meiotic transition within a cyst depend on the ICB component <i>Tex14</i>, which we show is required for functional cytoplasmic sharing. We find that <i>Tex14</i> mutants more rapidly attenuate the pluripotency transcript <i>Dppa3</i> upon meiotic initiation, and <i>Dppa3</i> mutants undergo premature meiosis similar to <i>Tex14</i> Together, these results lead to a model that ICBs coordinate and buffer the transition from pluripotency to meiosis through dilution of regulatory factors.