Scientists who study the physical structure of the brain typically slice the organ into thin sections that are then digitized and analyzed using specialty software that allows rendering of 3D volumes. Yet, just like with walls, the only reason we can’t see through brains is because they are opaque. This may sound like a tautology, a fact of life that will always be, yet it turns out that the main reason brain tissue is not transparent is its lipid content.
Taking note of this fact, researchers at Stanford University developed a chemical process of removing fat content from brain tissue and replacing it with a mix of formaldehyde, a hydrogel, and other ingredients. Called Clear Lipid-exchanged Anatomically Rigid Imaging/immunostaining-compatible Tissue Hydrogel, or CLARITY, the technique should be effective for other tissue types, allowing both structural and molecular analysis while preserving the 3D shape and functional integrity of the samples.
Here’s an interview with Karl Deisseroth, MD, PhD, the lead author of the study:
A couple videos showing off imaging done on a transparent mouse brain:
Study in Nature: Structural and molecular interrogation of intact biological systems
NIH announcement: Fat-free see-through brain bares all…
More from Stanford Medicine Scope Blog: Lightning strikes twice: Optogenetics pioneer Karl Deisseroth’s newest technique renders tissues transparent, yet structurally intact