Fly eye. Light micrograph of a section through the eye of a fruit fly (Drosophila sp.). Flies have compound eyes, each containing hundreds of separate image-forming facets (ommatidia), here outlined in bright blue. These tiny facets are cone-shaped in structure, and consist of a lens and seven rhabdoms (dark blue dots). The rhabdoms are light sensitive cells which transmit nerve signals to the sight centers of the brain. The separate images from each facet are combined by the fly's eye to form one view of the surroundings. Phase contrast. Magnification: x100 at 35 mm size.