A human brain comparable with that of a five-week-old foetus has been grown in a laboratory dish.
The organ – which is about the size of a rubber on the end of a pencil – was created from skin cells that were genetically altered by US scientists.
They hope the lumpy mass of functioning nerve cells and fibres will help them research brain disorders such as Alzheimer’s and test new drugs.
As well as neurons and their signal-carrying branches – axons and dendrites – the brain also contains immune cells. It has around 99 percent of the genes present in a foetal brain, a rudimentary spinal cord and even the beginnings of an “eye”.
Professor Rene Anand, of Ohio State University, where the brain was grown, said: “We’ve struggled for a long time trying to solve complex brain disease problems that cause tremendous pain and suffering. This brain model… gives us better and more relevant options to test and develop therapeutics.”