Rainbow Potential

What am I looking at?

This is a fluorescent microscopy image of an embryonic chameleon’s skin, with individual cells distinguishable within the scales. The nuclei of these cells are blue (1). The actin protein within the cytoskeletons of the cells is stained green (2). And the red dots are nerve cells (3).

Biology in the background

Chameleons change the color of their skin using specialized cells called melanophores and iridophores. Melanophores contain the pigment melanin, a pigment that is in human skin as well. However, unlike humans, chameleons can move melanin within their cells to make it more or less dense. More densely packed melanin makes their skin darker, while more dispersed melanin makes their skin lighter. This gives chameleons control over the tone or intensity of their skin color.

And to change its actual color they use cells called iridophores, which are packed with nanocrystals made of the amino acid guanine. These crystals refract (bend) or reflect light in different ways depending on the density and orientation of this crystal lattice. For example, when a chameleon’s skin is relaxed, the crystals are arranged in a dense lattice, resulting in red or green coloration. But if a chameleon encounters a rival, it can tighten the cells in its skin, spreading out the lattice and causing it to reflect colors such as yellow. This gives chameleons some control over what color they appear to the world around them.

One of the larger embryonic scales in this image is about 200 micrometers across, or roughly 2.5 times larger than the width of a human hair.

Technique

This image was created using confocal microscopy.