Final answer:
In the developing nervous system, cells undergo a process called migration. They move from the neural tube, formed from the ectoderm layer of the embryo, to become either the brain or the spinal cord.
Step-by-step explanation:
In the developing nervous system, cells complete a journey in a process known as migration. Early in embryonic development, the outer layer of the embryo, the ectoderm, gives rise to the skin and the nervous system. A specialized region of this layer, the neuroectoderm, becomes a groove that folds in and becomes the neural tube beneath the dorsal surface of the embryo.
The anterior end of the neural tube develops into the brain, and the posterior region becomes the spinal cord. Tissues at the edges of the neural groove, when it closes off, are called the neural crest and migrate through the embryo to give rise to various structures. The most prominent cell of the nervous system, the neuron, displays a distinctive morphology including a cell body, dendrites and an axon. Many axons are wrapped by a myelin sheath, a lipid derivative that acts as an insulator and speeds up the transmission of the action potential.
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