What are the major events of neurulation?
-neuroectoderm appears along the length of the embryo
-neuroectoderm thickens to form a neural plate
-neural plate sinks and the edges thicken, forming a neural groove with a raised neural fold
-cells along the lateral margins of the fold become specialized neural crest tissue
-neural folds fuse, beginning with the cervical region and progressing rostrally (towards the head) and caudally (towards the tail)
-at 4 weeks, the neural tube is formed