Yellow 5 Dye Can Make Mice Translucent

A study published in the creatively named science journal Science reveals that applying Yellow 5 dye to a mouse’s skin opens temporary transparent windows into the animal’s body, essentially providing researchers with something akin to Superman’s X-ray vision.

The technique of slathering a mouse with dye from the grocery store baking section was developed by researchers at Stanford University who believe this could be a new method of observing biological processes and internal organs without invasive procedures. It’s a clever little hack that harnesses the power of light scattering and something called a refractive index, which is a measure of how light bends as it passes through a material. Flesh is made up of water, proteins, and fats which all scatter light, giving that opaque look when you, for instance, hold the flashlight up to your finger.

Tartrazine, the scientific name for Yellow 5, allowed the researchers to adjust the refractive index of skin tissue, which reduced light scattering and let red and orange light to penetrate more deeply into the skin— so deep they could see the mouse’s organs. It’s gross! It makes the poor mouse look like its skin has been flayed. But it hasn’t. It’s perfectly fine. The translucent effect wears off as soon as you wipe away the dye or, more likely, when it fades because anyone who’s ever had to dye a buttercream frosting for a cake knows that stuff stains like a motherfucker.

There are tons of practical applications for this discovery. Researchers can potentially and noninvasively observe organ function, track blood flow, and take a gander at muscle contractions by opening up a harmless little window into a test subject’s body. No need for exploratory surgery or maybe even a biopsy when you could just see directly into a creature’s soul.

It has not been tested on humans yet, but just think of the possibilities. If you have tricky veins that nurses have trouble pinning down to draw blood, just imagine how much easier their job would be if they could see through your skin. Then you’d really have justification to yell at them when they inevitably still screwed up and stab your arm like they’re tenderizing a chicken breast.

There are limitations. So far researchers can’t make bones see-through, and there are inconsistencies in the levels of translucency in different types of tissue. They should also probably make sure rubbing a bunch of dye on skin doesn’t give you cancer or whatever. 

But so far the research does look promising. Don’t be surprised if one day in the near or distant future your doctor coats your chest with what looks like a bottle of piss and then stares at it for a bit as you wonder if the sounds he’s making are an inquisitive “Hm” or a titillated “Mm.”