There's still an awful lot that's not understood about how complex biological systems (like our bodies) really work. Part of the problem is that we can't just go look, since the only way to really see inside a brain (for example) is to cut it open, which by definition destroys its structure. Japanese scientists have a better idea: just turn everything transparent.
Scientists from Japan's RIKEN Brain Science Institute have been testing a new chemical reagent called Scale that can make just about any kind of tissue more or less completely see-through. By using genetic modification to cause certain types of cells to fluoresce, it then becomes possible to generate exceptionally detailed and intricate images of even the most delicate biological structures. The picture below, for example, shows the network of neurons inside a small area of a mouse brain:
By now, you've probably guessed the problem with this technique: it doesn't work on living tissue. Or rather, it does work on living tissue, but that tissue rapidly becomes non-living. The nastiness of the chemical is directly proportional to the amount of transparency it creates, though, so the researchers are hoping that if they dial it back a little bit, they might be able to get it to work in living tissue as well. Now, who wants to be invisible?