The living skeletal muscle tissue grown by Duke University researchers is 10 times stronger than any previously bioengineered muscles. Not only does it contract as strongly and as rapidly as the real thing, but it is also capable of self-healing, both in the lab and after implantation into an animal. This has been proven beyond doubt through a novel approach that involves peeking at the growing muscle tissue through a glass window in the back of a living mouse.

Aided by Greg Palmer, an assistant professor of radiation oncology in the Duke University School of Medicine, the team of researchers placed their newly-developed muscle into a dorsal window chamber sealed with a transparent panel made of glass. The resulting peephole was then used to monitor the implanted tissue every second day over a two-week period.

The observation process must have been pretty spectacular. Not only were the strands of engineered muscle fiber stained to enable tracking their growth, but they were also coaxed into giving out fluorescent flashes whenever the muscles would contract, in response to sudden increases in calcium levels. As the muscles grew stronger, the flashes gradually picked up in intensity. Gradually, more and more veins grew into the implanted muscle fibers.

They WATCHED living muscle grow?! That's incredible.

So wait, is it considered life if we can just grow a muscle on its own?