Scientists at UC Davis say they've grown miniature human brains in a lab.
The millimeter-long brain tissue, grown from stem cells, was implanted into a mouse where it grew its own blood vessels.
Researchers hope the study can one day help stroke victims, but they say there's still a lot of work to be done.
The lab-grown brains die after reaching a certain size and don't have the ability to process information.
The research was published last month in the journal "NeuroReport."