Polarity in Drosophila oocyte - gurken mRNA

The localisation of gurken mRNA in the Drosophila oocyte defines the dorsal-ventral axis of the embryo. This in situ hybridisation to gurken mRNAs is 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. Gurken is translated on the dorsal side, producing a secreted signalling molecule that induces the adjacent follicle cells to adopt a dorsal rather than a ventral fate, and this defines the polarity of the embryo's dorsal- ventral axis. Length of whole egg chamber is about 400 microns.