“We combined the yellow dye, which is a molecule that absorbs most light, especially blue and ultraviolet light, with skin, which is a scattering medium. In essence, the dye molecules reduce the degree to which light scatters in the skin tissue, like dissipating a fog bank. In their experiments with mice, the researchers rubbed the water and dye solution onto the skin of the animals’ skulls and abdomens. Once the dye had completely diffused into the skin, the skin became transparent. But now that we can make tissue transparent, it will allow us to look at more detailed dynamics.