See-through mice may bring to mind an image from a science fiction movie, or maybe a horror movie, but this is no movie magic. Researchers have found a way to make mice transparent.

The study was led by Viviana Gradinaru from the California Institute of Technology. Her experiences making mice transparent were published the journal Cell.

Don't worry about seeing one scurry across the floor or in the garage though, as the rodents are dead, and are only used for research purposes to help scientists understand rat anatomy. Additionally, only the rat's organs are transparent. Its bones are still solid.  

The process involves euthanizing the rat and peeling off all its skin. Then researchers pumped several different chemicals, such as detergent, through blood vessels and passages in the brain and spinal cord.

This technique is helpful because mice are considered model organisms, meaning they are very similar to humans in the bodies and bodily mechanisms. In other words, these transparent mice may help researchers make progress in understand the human body and human diseases.

Gradinaru said it takes a week to create a transparent mouse and two weeks to create a transparent rat.

The rodents look very similar to jello covered mouse parts, but are very helpful in understanding rat anatomy.

Gradinaru said to New Scientist that they are working to map the rat's nervous system in order to create more effective treatments for diseases, such as Parkinson's disease, that involve the nervous system.

The technique to create these transparent rodents plays off an earlier victory from a group of Stanford scientists who made a mouse's entire brain transparent.

In the study, they treated the brain with formaldehyde to essentially freeze the brain cells and processes while preserving the tissue. Then they soaked the brain in acrylamide to bind to proteins and create a matrix. Then the brain was washed with detergent and placed in an electric field to dissolve the lipids. After a few weeks, they ended up with a transparent brain.

In Gradinaru and her colleagues' technique, they removed the rat's skin and pumped detergent into the mouse's circulatory system. Then they removed any large bones that got in the way and pumped fluorescent chemicals into the animal to visualize cells.

This technique may someday be used to look for cancerous cells in human skin biopsies.

Another researcher at Stanford, Karl Deisseroth, is developing a transparency technique that may yield a transparent human brain.