Scientists have for the first time grown a complex, fully functional organ from scratch in a living animal by transplanting cells that were originally created in a laboratory.
British scientists produced a working thymus, a vital immune system "nerve centre" located near the heart.
In future the technique, so far only tested on mice, could be used to provide replacement organs for people with weakened immune systems, scientists believe.
But it might be another 10 years before such a treatment is shown to be effective and safe enough for human patients.
More top news
Singer Barry Manilow is out of surgery and doing well after the singer was rushed to hospital following a performance in Memphis.
A factory owner who created a Hungarian "slave workforce" to supply beds to big-name retailers like John Lewis has been jailed.
The boyfriend of EastEnders actress Sian Blake is charged with murdering her and their two children.