Achieving optical transparency in live animals with absorbing molecules
…an aqueous solution of a common food color approved by the US Food and Drug Administration, tartrazine, has the effect of reversibly making the skin, muscle, and connective tissues transparent in live rodents.
The food coloring used in Doritos and Mountain Dew can make mouse skin transparent in high concentrations. I originally saw an article about this on The Onion and thought it was a joke, but it’s legit!