Using food coloring, researchers manage to make mice’s skin transparent

Using tartrazine, a dye found in several food products, researchers at Stanford University were able to observe various vital organs in mice.

Tartrazine is a yellow-orange dye and can be found in candy, ice cream, or chips. Researchers at Stanford University in California smeared it on the stomach, thighs, and skulls of living mice, which made these areas partially transparent in a few minutes, revealing the organs located just under the skin. These scientists were thus able, for example, to observe with the naked eye or through microscopes, the liver, the bladder, the digestive organs at work. Blood vessels that supply the brain, or even muscle fibers contracting. These experiments were described, Friday, September 6, in the very serious journal Science.

A dye that can make skin transparent, a priori, it is counterintuitive, but this mechanism is linked to principles of physics and optics. Here the dye, by reducing the diffusion of certain light waves inside the tissue, and by allowing other rays of the light spectrum to penetrate more deeply, modifies the contrasts of the image, which gives this impression of transparency. This is limited to the area soaked by the product, that is to say the few millimeters of thickness of the skin only. This phenomenon is reversible when the dye dissipates.

Could tartrazine have the same effect on humans? This is a real question, because mice have skin 10 times thinner than ours! In them, it is easy to get past this barrier, but in humans, it would be necessary to manage to administer the dye over the entire thickness of the skin, by patches or micro-injections, to see what is just behind, which has not yet been tested. This technique, if it were transposable, would open up, for humans, the prospect of controlling the state of veins, monitoring digestive disorders, observing what is happening under certain skin lesions, or under moles, for example, without making an incision. This yellow dye, code name E102 on the packaging is therefore promising but its safety, in a use other than as a food additive, will first have to be proven.