Examville

 

Development of the Neural Tube

-begins in the third week and is completed in the fourth week. A. Neural plate - is a thickened pear-shaped region of embryonic ectoderm, located between the primitive knot and the oropharyngeal membrane.

 

B. Neural groove – forms as the neural plate begins to fold inward. -is flanked by neural folds, which are parallel. -deepens as the neural folds begin to close over it. C. Neural folds – -fuse in the midline to form the neural tube. -are the sites of neural crest cell differentiation. D. Neural tube -forms as the neural folds fuse in the midline and separate from the surface ectoderm. -lies between the surface ectoderm and the notochord. -gives rise to the CNS: • The cranial part becomes the brain. • The caudal part becomes the spinal cord. • The cavity gives rise to the central canal of the spinal cord and ventricles of the brain. The two openings in the neural tube connect the central canal with the amniotic cavity: a. Anterior neuropore -closes in the fourth week (day 25) and becomes the lamina terminalis. b. Posterior neuropore- closes in fourth week (day 27)