Scientists grow human brain tissue inside mice

Stanford Medicine scientists successfully implanted human cortical organoids into genetically engineered mice lacking most of their own cortex, creating hybrid xenocortical mice. The human neurons survived, grew, formed neural circuits, and connected with mouse spinal cord. Within months, over 90 percent of cortical tissue was human origin, revealing rare von Economo neurons never before seen in lab culture.

These animal models offer a unique opportunity to study how disease-associated alterations in human brain circuitry manifest in an intact nervous system.