Eye on the Fly

What am I looking at?

In this image, you can see the fly eye (1) and the part of the fly brain that processes visual information – known as the optic lobe (2). A specific class of photoreceptors (cells that sense light) called R7 photoreceptors are labeled in red (3); these cells allow the fly to detect ultraviolet light, a wavelength of light that humans cannot see. A specific type of visual processing cell called CT1 is labeled in green (4); these cells help convert the light information gathered by the eye into visual information for the brain to interpret. Finally, connection points between neurons, also known as synapses, are indicated by the small blue dots (5).    

Biology in the background

The fruit fly eye is considered compound because it has many small chambers laid out on a convex (curving outward) surface; each chamber can sense light. The optic lobe is the part of the brain that synthesizes and processes the visual information that’s gathered by the eye. As you can see in this image, a fruit fly’s optic lobe is located very close to the eye itself, whereas the optic lobe of a human is located all the way in the back of our brain, almost as far away from our eyes it could get.  

The eye of a fruit fly is about 0.08 millimeters wide, or roughly the same width as a human hair.

Technique

This image was taken using fluorescence microscopy.