Organogenesis

The nervous system develops from a section of the ectoderm called the neural plate, which begins to differentiate under the influence of the nearby notochord and paraxial mesoderm around the third week.

The neural plate becomes the neural tube, which gives rise to the brain and spinal cord, the central nervous system.

Peripheral nervous system (PNS) is derived from three sources:

1. Neural crest cells
2. Neural tube, which gives rise to all preganglionic autonomic nerves (sympathetic and parasympathetic) and all nerves (a-motoneurons and g-motoneurons) that innervate skeletal muscles
3. Mesoderm, which gives rise to the dura mater and to connective tissue investments of peripheral nerve fibers (endoneurium, perineurium, and epineurium)

Nervous System

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