(BBC News) Miniature "human brains" have been grown in a lab in a feat scientists hope will transform the understanding of neurological disorders.
The pea-sized structures reached the same level of development as in a nine-week-old fetus, but are incapable of thought.
The study, published in the journal Nature, has already been used to gain insight into rare diseases.
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Neuroscientists have described the findings as astounding and fascinating.