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How do the neural plate and neural tube form during early nervous system development?

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Fetal growth — human development Growth of the human fetus from the fourth month to the ninth month of pregnancy.

In early vertebrate development, the nervous system originates from the ectoderm, the outermost of the three primary germ layers.12

Formation of the Neural Plate

Around the third week of human development, the ectoderm along the dorsal midline of the embryo thickens to form the neural plate. This process occurs above the notochord, an axial rod of mesodermal tissue that serves as a temporary structural support. The neural plate serves as the foundational rudiment for the entire central nervous system.213

Formation of the Neural Tube

The transformation of the neural plate into the neural tube occurs through a process called neurulation:1

Neural Grooves and Folds: A gutterlike depression known as the neural groove forms in the midline of the neural plate, flanked by raised edges called neural folds.13
Convergence and Fusion: These neural folds rise and converge toward the midline, where they eventually meet and fuse together.23
Detachment: Once fused, the structure forms a closed tube that detaches from the overlying surface ectoderm and sinks beneath the surface.23

The anterior portion of this tube expands to become the brain, while the narrower posterior portion develops into the spinal cord. Additionally, neural crest cells dissociate from the tube during this process to form various structures, including elements of the peripheral nervous system.4213