An image of the zebrafish brain neuronal development (dorsal view) at 4 days post-fertilization.
Three components of the neural network are seen in this image. Neuropil, or dense areas of interwoven neuron dendrites and axons, are shown in magenta and are clearly detectable in structures such as the eyes. Axon tracks are shown in green. A specific subtype of neuron called GABA-ergic cells, which use the inhibitory neurotransmitter GABA, are seen in cyan.