Central Nervous System Development : Neural Induction, Neurogenesis, Migration, Axon Guidance, And Synaptic Development

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The major processes involved in central nervous system development are neural induction, neurogenesis, migration, axon guidance, and synaptic development/plasticity. Neural induction is the process by which the neural plate forms. Some of the regulatory mechanisms of neural plate formation are due to extrinsic signaling. The mesoderm, specifically, the notochord, sends signals to specific ectodermal cells. These signals cause the ectodermal cells to commit to becoming neural progenitor cells and form the neural plate. After the neural plate forms, the neural tube begins to form. This happens as the neural plate begins to fold. It separates from the rest of the ectoderm. The ends of the plates fuse, forming the neural tube. After the neural tube forms, the cells’ fates are determined and neurogenesis occurs. Often, this neurogenesis/ cell fate determination stage overlaps with migration. Cell fate determination is regulated by many factors, including extrinsic signaling, intrinsic signaling, location/cell migration pathway, and timing of differentiation. One example of extrinsic signaling is notch signaling. In a proneural cluster, there is initially an equal amount of notch and delta signaling. However, one cell starts expressing a higher amount of delta. This signals the other cell to express a lower amount of delta. The imbalance in signaling is amplified. The cell with a higher amount of delta signaling becomes specified as a neuroblast, and the cell that has higher

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