Scientists find growing brains are made from two separate systems

UPDATE - follow-up to How to make a brain: new experiments challenge existing picture - nature.com: New laboratory tests show the human brain forms from two separate nervous systems that join together instead of growing from a single source. Recent findings reveal the developing brain contains two distinct organs that evolve independently during early growth. Researchers working on neural ectoderm progenitors discovered these parallel parts before they merge into one main structure.