During which stage of embryonic development does the neural tube form?

Around the third week of gestation, the notochord sends a molecular signal that causes the cells of the ectoderm just above it to thicken into an individualized epithelial column, the neural plate. After this “neural induction”, the neural plate begins to invaginate to form the neural groove, which then rises from the embryo’s surface and closes to form the neural tube.

It feels feed the echo system