To many consumers, "Yellow No. 5" is best known as the food dye that adds an orange-yellow tinge to snacks and drinks like Doritos, Gatorade, and M&Ms. To a team from Stanford, however, tartrazine, the chemical found in that dye, recently served as a window into living creatures' bodies, effectively making the skin of mice transparent.
- The experiment: For their study published Friday in the journal Science, the researchers rubbed a tartrazine solution onto various parts of lab mice, including their stomachs, scalps, and hind legs, reports the Washington Post. In just minutes, the mice's skin turned "temporarily into a living window, revealing branching blood vessels, muscle fibers, and contractions of the gut," per the Post. "You could see through the mouse," says Adam Wax of the National Science Foundation, which helped fund the study. "I've been working in optics for 30 years, and I thought that result was jaw-dropping."