Complete invisibility remains out of reach for scientists, but researchers at the University of Tokyo have gotten pretty darn close with a new procedure that renders lab mice almost entirely transparent. Unfortunately, the mouse is killed in the process.

The two-week-plus process rids the mouse of a compound called haem, the chemical component that gives blood its red color and colors most tissues in the body. To complete the process, researchers from the University of Tokyo and the Japan Science and Technology Agency pump a saline solution through the mouse's heart, forcing the animal's blood out of its circulatory system.

Of course, without blood, the mouse quickly expires. Next, scientists pump a reagent into the mouse's circulatory system, which pulls any remaining haem from the haemoglobin in the animal's innards. Finally, the now very dead mouse is skinned and soaked in the same reagent for two weeks.

As scientists have detailed in a recent paper -- published this week in the journal Cell -- the tissue decolorization process, when coupled with light-sheet fluorescent microscopy, allow researchers to capture extremely detailed images of the mouse's interior, biological systems and individual organs.

In addition to high-definition imagery of mouse brains, hearts, lungs, kidneys, and livers, scientists were also able to use the transparency technique to create 3D images of organs without cutting into the specimen.

Worryingly, the researchers say the technology could be adapted to help scientists craft whole 3D images of human organs, like the brain.

"This new method could be used for 3D pathology, anatomical studies, and immunohistochemistry of entire organisms," lead researcher Hiroki Ueda said in a recent press release. "For example, it could be used to study how embryos develop or how cancer and autoimmune diseases develop at the cellular level, leading to a deeper understanding of such diseases and perhaps to new therapeutic strategies."

"It could lead to the achievement of one of our great dreams, organism-level systems biology based on whole-body imaging at single-cell resolution," he added.