The Larval Optic Nerve Is Required for the Development of an Identified Serotonergic Arborization in Drosophila melanogaster

The larval visual system in the fruitfly Drosophila melanogaster consists of two bilateral clusters of 12 photoreceptor cells. These neurons send their axons in a fascicle, the Bolwig's nerve, toward the target area in the ventral lateral region of the brain hemispheres. We describe the development of a serotonergic arborization originating in the central brain found in the larval optic center in association with the larval optic nerve. This …