Scientists shrank mice's brains and replaced the missing tissue with human 'organoids': Scientists have devised a new way to incorporate human brain tissue into living mice, opening the door to new research.

In a new study, scientists reared lab mice that were missing sections of their brains and then replaced the missing tissue with human cells.

The experiment represents a step forward in the study of human brain organoids ‪—‬ tiny models of the human brain grown from stem cells. In the long run, scientists aim to use organoids to better understand how the brain develops and how its structure and function change in the context of disease.