solution = liquid solution?

Context:

Combining an imaging technique called multiphoton microscopy with "optical clearing," which uses a solution that renders tissue transparent, the researchers were able to scan mouse organs and create high-resolution images of the brain, small intestine, large intestine, kidney, lung and testicles.

They then created 3D models of the complete organs -- a feat that, until now, was only possible by slicing the organs into thin sections or destroying them in the process, a disadvantage if more information about the sample is needed after the fact.

http://www.sciencedaily.com/releases/2010/06/100624131439.htm