Scientists have made partly functioning rat lungs in the laboratory, a small yet tantalizing step in the quest to create fresh body parts for transplantation or to treat disease.

A team led by researchers from Yale University took apart rats' lungs and rebuilt them with new cells in a glass jar. When transplanted into live rats for a few hours, the new organs successfully exchanged oxygen and carbon dioxide, just as natural lungs do. The findings are published in the online version of the journal Science.

The...