The ventral, motor region is more advanced than the dorsal sensory area and likewise the cephalic areas better developed than caudal regions. In the cervical regions, the dorsal funiculus develops and reaches down to the level of the 2nd cervical segment. As canalization continues in the caudal most region of the neural tube, the tail begins to show the first signs of regression. Various tracts and fibres in the spinal cord exist as continuations of those in the rhombencephalon. With the beginning of chondrification of the neural arches of the vertebrae, the future neural canal is distinguishale.
Condensed mesenchyme joins the arch tips round the dorsum of the spinal cord.