It’s a high school biology student’s dream come true: all the educational perks of frog dissection without having to lift a scalpel. Japanese researchers have developed a frog (video) with skin so transparent that its internal organs are visible. More than a boon to squeamish students, the see-through frog could aid biologists studying how organs develop and respond to tumors or toxins.
The Hiroshima University team, led by Masayuki Sumida, created the frog by breeding garden-variety Japanese brown frogs that had recessive genes for light-colored skin. About one-sixteenth of the second-generation tadpoles grew up to be transparent. They will be useful in the lab, says Santiago Castroviejo-Fisher, a zoologist at Uppsala University in Sweden, because their organs can be monitored in real time to see how they respond to stimuli. “When you kill the organism, you have a snapshot of that moment in time, but you cannot follow a process,” he explains.
Transparent frogs exist in the wild as well, says Castroviejo-Fisher, who has discovered several new species of so-called glass frogs. About 150 species live in the treetops of Central and South American rain forests, where transparency most likely evolved as a form of camouflage. But this kind of disguise is probably rare because frog innards are susceptible to harm in direct sunlight, he adds. The selectively grown frogs in Japan don’t have to worry about harmful light, though—they won’t get out of the dull glow of a lab’s fluorescent bulbs.