Drosophila embryo polarity - bicoid mRNA

The localisation of bicoid mRNA in the Drosophila oocyte defines the anterior-posterior axis of the embryo. The image shows in situ hybridisation to bicoid 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. Bicoid mRNA localises to anterior of the oocyte, directing where head and thorax of the embryo develop.