On the left: A mouse embryo preserved in para-formaldehyde. On the right: A mouse embryo soaked in Scale for two weeks.

What’s the News: The trouble with brains, organs, and tissues in general, from a biologist’s perspective, is that they scatter light like nobody’s business. Shine a light into there to start snapping pictures of cells with your microscope, and bam, all those proteins and macromolecules bounce it around and turn everything to static before you’ve gotten more than a millimeter below the surface. Scientists at RIKEN in Japan, however, have just published a special recipe for a substance that makes tissue as transparent as Jell-O, making unprecedentedly deep imaging possible.

How the Heck:

Substances to make tissue more transparent are called clearing agents, and the ones we have now have varying degrees of penetration—in other words, they don’t always take you as deep as you’d like. To boot, they sometimes mess with the fluorescent tags that biologists splice into certain tissues to light up a particular set of blood vessels or neurons, for example.
This recipe clears out tissue so well that the only limitation on how deep you can see is the power of ...