Tiny human almost-brains made in lab

Stem cells arrange themselves into a version of the most complex human organ

LIKE A BRAIN  A cross section of a lab-grown approximation of a human brain reveals several features, including neurons (green) and neuron-producing stem cells (red).

Madeline A. Lancaster

Largely left to their own devices, human stem cells knitted themselves into tissue with a multitude of brain structures and specialized cadres of neurons in a form reminiscent of the brain of a nine-week-old fetus, scientists report August 28 in Nature.