Unfortunately for millions of mice and rats in laboratories across the world, their internal organs are extremely important for the advancement of science, giving researchers a chance to study biological processes and test out experimental treatments. To make this a little easier on all concerned, scientists have now developed a technique to turn rodents’ bodies see-through, which should make observing their innards less complicated while also reducing the number of furry “volunteers” required for research.
The main catch for the animals, however, is that they have to be dead in order for this to work. Describing the process in the journal Nature Methods, researchers explain how they used organic solvents to remove all the water and lipids from rodents’ bodies, making their organs totally transparent.
The technique is an advancement on a previous method called 3D imaging of solvent-cleared organs (DISCO), and has therefore been dubbed uDISCO, which stands for ultimate DISCO. Like cooking a chicken, the removal of water and fats causes the animals’ bodies to shrink considerably, with the majority of the remaining tissue being made up of protein.
By staining these proteins with fluorescent markers, scientists can use these transparent rodent bodies to observe complex internal structures and processes in the finest detail, while also observing entire bodies at once. This should help them cut down on the number of animals needed for studies, as up to now researchers have tended to focus on a single organ and throw the rest of the body away.
To test out the new technique, the study authors imaged the neuronal connections and blood vessels across the entire body of a shrunken, transparent mouse. In doing so, they were able to generate high-resolution images of these systems, revealing individual neurons and their connecting arms – known as axons and dendrites.
In the future, they hope to see uDISCO used to study neurodegeneration in diseases that affect the entire nervous system – such as amyotrophic lateral sclerosis (ALS) – as well as a range of other purposes.