Researchers from Japan’s RIKEN institute announced in April that they have grown skin from mouse stem cells in a process that one day may help skin graft recipients. Unlike earlier lab-grown skin, the new version, highlighted in green, has not just one but all three layers of skin, complete with hair follicles and oil-producing glands. Researchers used furry mice to help the stem cells grow to maturity before transplanting them to naked mice, where hair soon took root.