Figure 1

Overview of three types of Drosophila neurons. (a) Larval mushroom body interneurons. These neurons were marked by crossing flies containing the mushroom body Gal4 driver 201Y with flies containing a UAS-mCD8-GFP transgene. Brains were dissected from third instar larval progeny. A projection of a confocal image stack is shown. The structure is shown schematically to the right, and a diagram of a single neuron is shown at the lower right. (b) Olfactory projection interneurons. These neurons were marked by crossing GH146 Gal4 and UAS-mCD8-GFP flies. Brains from third instar progeny were dissected and a projection of a confocal stack is shown. The GH146 Gal4 driver also expresses in the optic lobe, which accounts for the bright GFP in the lateral region of the brain. Different compartments of the projection neurons are outlined. The axon projections are outlined to their synapses on the mushroom body calyx, but the continuation to the lateral horn is not outlined as the axons become more difficult to follow. (c) Sensory neurons in the dorsal cluster, including dendritic arborization neurons. Neurons were labeled by crossing elav-Gal4 and UAS-mCD8-GFP flies. Confocal microscopy was used to image just below the cuticle of whole, live early second instar progeny; a projection is shown with the scale inverted for clarity. Cell bodies are in the center of the image. Anterior is left and dorsal is up. Dendrites project dorsally and branch extensively just under the cuticle. Axons project down and form a tight bundle.