From autopsies to a drop of blood on a microscope slide, the history of modern medicine is very much about peering inside the body. Now, researchers at the California Institute of Technology have figured out a way to do that without having to cut a creature open.
Based on her earlier work making mouse brains transparent, Dr Viviana Gradinaru, the senior author of a study released this week in the journal Cell, tweaked the method and created what is very likely the world's first see-through mouse.
To create her blob-like rodent, Dr Gradinaru first euthanized the critter and removed its skin. She then filled the mouse's circulatory system with a gel that worked its way into the rodent's organs and clarified them by dissolving the fats they held.
The gel also helped stabilize the tissues in the body so that the mouse didn't completely disintegrate. It took two to three days for the kidney, heart, lung and intestines to clear and about two weeks for the brain and the rest of the body to become transparent.
"Although the idea of tissue clearing has been around for a century, to our knowledge, this is the first study to perform whole-body clearing, as opposed to first extracting and then clearing organs outside the adult body," Dr Gradinaru said in a statement. "Our methodology has the potential to accelerate any scientific endeavor that would benefit from whole-organism mapping, including the study of how peripheral nerves and organs can profoundly affect cognition and mental processing, and vice versa."
In other words, now that the scientists can see what goes on inside the body without having to destroy part of it to look, they can better map the way certain diseases and neurological processes happen. This could help the study of disorders of the nervous system such as Parkinson's, a particular research interest of Dr Gradinaru.
"Given increasing interest in the link between the brain and major organ systems, it will be critical to have an unsegmented view of the whole body, with structural connections between the brain and other major organs left intact," the paper concludes.
Transparent mice look pretty gross, yours truly concludes.