epidermis

"We discovered at least two different stem cell populations -- one that regenerates tissues such as epidermis and neurons, and another that forms muscles and connective tissue," says Adelmann.

The epidermis, the top layer of the skin, protects the body from external aggression.

"As alternatives to autologous skin grafts, artificial skin substitutes including cultured epidermis and reconstituted skins have been developed," says the lead author of the study Dr. Hisato Nagano.

With this delivery method, drugs can pass through the tough outer layer of the epidermis, which can't be penetrated by creams applied to the skin.

In insects, specific genes became specialised in muscles and in the epidermis for cuticle formation, contributing to their ability to fly.