(A) Representative confocal image of a stage 17 embryonic head with Dfd expressing cells (purple), Myosin expressing muscles (blue) and FasII expressing axonal projections (green) highlighted. The MN2a is identified as a Dfd expressing neuron projecting a FasII expressing axon to the Dfd positive MHE muscle. This stereotypic innervation is the basis for identifying wiring defects after RNAi interference shown in (D). 