announced that they could turn mouse embryos transparent with a potion ... um, make that scientific reagent ... called "Scale." In terms of the picture above, you'd soak the thing on the left and get the thing on the right. I could go in my lab and mix up some Scale right now, it's just a common lab detergent and the common chemical urea with a few other things (you know, eye of newt, etc.).
If this seems like being Harry Potter going down to Snape's dungeon to mix up a Transparency Potion, that's not far off. But of course the big difference is, if this is chemistry and not alchemy, we can find a mechanism for the change.
What Scale does is changes the refractive index of the embryo as it soaks through it, changing all the different refractive indices of cell membranes and proteins and organelles into one refractive index. Uniform refractive index + disordered arrangement of stuff = no scattering of light, so the light shines right through. From the reagents involved I'm guessing this involves unfolding proteins and disrupting membranes gently. There are limitations, in that Scale transparency-izes dead embryos, not live creatures for example (Scale is NOT one of the Deathly Hallows), but it's still very cool and lets us see things clearly that were formerly obscured.
Still, if you want to live magically, going into the lab to mix up a transparency potion from common chemicals is pretty close.