Seeing through science / Julia Calderon

Rodent corpses are made transparent using a new method

There is no doubt that peering into the bodies of animals leads to scientific discoveries. The 60s and 70s saw a flurry of research in developmental and genetic biology after laboratories began studying transparent creatures such as the nematode Caenorhabditis elegans)) and zebrafish Danio rerio)). The scientists could follow and see how young cells of these creatures develop into a whole body. Now, for the first time, they can also see through the bodies of mammals thanks to a technique that can make mice and rats, and possibly even larger animals, become transparent.

Scientists know how to do this in tissues such as mammalian brains, but the process can take months. To speed up the process and apply it on a larger scale, Viviana Gardinaro, a neurobiologist at the California Institute of Technology (Caltech), used rodent blood vessels in this way. The team injected the body of a dead rat with a series of chemicals that penetrated its tissues through the blood vessels. The substances replaced opaque lipids with a clear liquid. Within two weeks, the rat turned into a jelly-like specimen that you could see through. The researchers published their results in August 2014 in the journal Cell, along with pictures that are not recommended to look at while eating.

At the end of the process, Gardinaro was able to look at cells marked with dye or antibodies. This ability may help other researchers map nerve fibers or track cancer cells. "We can see things we couldn't see before," says Guangping Gao, a gene therapist at the University of Massachusetts Medical School who is interested in tracking viruses in the body. Gardinero says the technique can be applied to any creature that has a vascular system, even humans.