# Human brain organoids grafted into cortex-free mice

Researchers transplanted human brain organoids into the brains of mice lacking a cortex, where the tissue matured and wired itself into the animals' neural circuits. The method could give scientists an unprecedented way to study human brain development and disease in living animals, though it also fuels ethical debate over human-animal chimeras.

**Importance:** 3/5

## Sources

### Science
- [Nature](https://www.nature.com/articles/d41586-026-02967-7) — 2026-10-06