Neurulation is the process of folding of the neural plate and closure of the neural tube.
The notochord induces the ectoderm in the dorsal midline to thicken and form the neural plate.
The edges of the neural plate, the neural folds, bend toward each other.
The neural folds meet dorsally and form the neural tube and the overlying epidermis.
This animation illustrates neurulation dynamically, with a three-dimensional perspective. Beginning with the bilaminar disc, the primitive streak advances dorsally and then recedes. As the embryo grows, the neural plate enlarges dorsally and the neural groove deepens. The neural folds meet in the midline near the center of the embryo to form the neural tube. Neural tube closure then proceeds both rostrally and caudally. Approximately 40 pairs of somites flank the neural tube. By embryonic day 28, the central nervous system is completely enclosed within the embryo.
