Drosophila embryo polarity - oskar mRNA

The localisation of oskar mRNA in the Drosophila oocyte defines the anterior-posterior axis of the embryo. in situ hybridisation to oskar mRNA in stage 10 Drosophila egg chamber. The egg chamber consists of 15 nurse cells and a large oocyte (right), which is surrounded by a layer of somatic follicle cells. Posterior localisation of oskar mRNA directs the formation of the pole plasm that contains the abdominal and germline determinants that pattern the posterior of the embryo.