Fig. 7. The polarised MT network fails to develop correctly in egg chambers of orbit⁶ mutants. (A-C) Egg chambers were stained to reveal Orbit/Mast (red), -tubulin (green) and DNA (blue). (A) Wild-type egg chambers at stages 1-, 5 and 7 showing the Orbit/Mast protein accumulates at the MTOC of the oocyte (arrowhead) and is present in the oocyte nucleus from stage 7 onwards (arrow). The punctate pattern of Orbit/Mast seems to show some correlation with the microtubule network (inset) of the egg chambers. (B) Egg chambers of 1- and 3- day old orbit⁶ females showing the age-dependent severity of the mutant phenotype. In egg chambers of younger females, the residual Orbit/Mast protein decorates a diminished number of microtubule bundles, which seem to contact local accumulations of Orbit/Mast (arrow). There is also reduced staining of a putative MTOC (arrowhead). (C) Colchicine-treated, wild-type stage 3 egg chamber showing no MTOC-specific localisation of Orbit/Mast. The microtubule network is destroyed and the Orbit/Mast staining is diffuse in the cytoplasm of cells. Scale bar: 10µm. (D) Wild-type egg chambers stained to reveal Orbit/Mast (red), lamin (green) and DNA (blue). Note the MTOC and nuclear localisation of Orbit and Mast, respectively. Scale bar: 20 µm.