They're building what ???

Scientists at Yale University recently took apart and then put back together rat lungs. WSJ.com reports, Scientists Build Rat a Lung, that this is one of the steps that have been taken in recent years by researchers in order to find a way to grow organs and other tissues for transplantation or for the treatment of disease one day. These "rebuilt" rat lungs actually worked successfully for a few hours.

Previously, scientists have successfully performed similar projects with rat hearts and livers. Doctors and scientists say this research is promising. However, they also say it will be years and maybe decades before such a project will be ready to be attempted on humans.