If your initial reaction is one of queasiness, it would be understandable: A new technique announced Monday in Nature Methods essentially allows scientists to make dead mice see-through—by stripping the lipids and water from the animals' tissues. The fat is what makes the tissues opaque; the removal of water is part of a shrinking process that leaves the body as little as 35% of its original size, which enables it to fit under a microscope, reports NBC News. The result is "like a transparent plastic mouse that you can bend," neuroscientist Ali Erturk tells the Wall Street Journal, and the implications could be huge. Scientists can currently get a look at the inside of animals with lo-res techniques like MRI, or can slice tissue into slivers to view under a microscope. With ultimate DISCO or uDISCO, scientists can use fluorescent proteins to "light up" specific cells, organs, or systems, providing a high-res, system-wide view.
And here's a problem with tissue slicing: Popular Science explains "cells are often too long to fit onto a tissue section," and so when it comes to studying neurons, "you are cutting the wires," says Erturk. "This will help us a lot with neuroscience, and especially diseases like Alzheimer's, Parkinson's, or MS and ALS, where the neural connectivity is lost," he tells Motherboard. And then there's the time-intensive nature of it: imaging wafer-thin slices of a mouse brain with an electron microscope and putting them together would take 50 years to complete, versus eight days to map a mouse brain with uDISCO. The slice-approach would take 1,000 years for a human brain, Erturk says, and using his technique on the human brain is the ultimate goal. "So far there is not any approach that even comes close to mapping any part of human brain at individual neuron level."