fuss transcript is expressed in 1 to 3 cells per hemineuromere in the embryonic central nervous system. In the third instar larva, fuss is detected in clusters of cells in the medioanterior protocerebrum, in the subesophageal ganglion and in the ventral nerve cord.

fuss transcript is detected in the embryonic and larval brain and ventral nerve cord. In the brain, the number of labelled cells increases significantly throughout embryogenesis, with the majority of these cells being located in the ocular protocerebrum. The number of labelled cells in the ventral nerve cord also increases, from one or two per segment, to three to five cells. At the later stage 16, expression is also detected in a single pair of cells adjacent to the midline. In third instar larvae, expression of fuss is detected in the dorsoanterior region of the brain, where the mushroom bodies will form, and in the subesophageal ganglion. In third instar larva, fuss transcript is expressed ubiquitously at low level in the CNS. In the brain, stronger expression is detected in groups of cells in the dorsoanterior region of the brain, where the mushroom bodies are located. In the ventral nerve cord, fuss trancript is expressed in 3 to 5 cells per segment.