Localised dynactin protects growing microtubules to deliver mRNA to the posterior cortex of the oocyte.

The localisation of mRNA to the posterior of the oocyte defines where the abdomen and germ cells form in the embryo. Kinesin 1 transports mRNA to the oocyte posterior along a polarised microtubule cytoskeleton that grows from non-centrosomal microtubule organising centres (ncMTOCs) along the anterior/lateral cortex. Here, we show that the formation of this polarised microtubule network also requires the posterior regulation of microtubule growth.