A single neuron is seen here in the midbrain of an adult transgenic zebrafish.
The neuron is expressing green fluorescent protein (GFP). The color relates to intensity of GFP, where low (black) to high (white) intensity follows the scale black, blue, purple, pink, red, orange, yellow, white.
This neuron has a profuse branching, tree-like structure (top) that extends out of the cell body (yellow/orange).
These finger-like projections act like tiny sensors, picking up information (multiple sensory inputs) and passing on messages to other cells in the nervous system
Other axons and fibres expressing GFP are also visible here (lower two-thirds of image).