Enlarge / Zihao Ou, who helped develop this solution, holds a tube of it. One key challenge in medical imaging is to look past skin and other tissue that are opaque to see internal organs and structures. This is the reason we need things like ultrasonography, magnetic resonance, or X-rays. There are chemical clearing agents that can make tissue transparent, like acrylamide or tetrahydrofuran, but they are almost never used in living organisms because they’re either highly toxic or can dissolve away essential biomolecules. But now, a team of Stanford University scientists has finally found an agent that can reversibly make skin transparent without damaging it.