Abstract
During embryogenesis, the construction of the nervous system requires that nerve cells connect very precisely to each other and to peripheral tissues. Establishment of these connections involves the growth and extension of long thin processes, known as axons, from the main body of the cell. The tip of this growing axon displays a highly specialised and dynamic structure, called the growth cone. Growth cone sense information presented to it in the embryonic environment and respond by steering axon growth towards the correct targets.
Key Concepts:
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The growth cones of growing nerves control axon outgrowth and direction.
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Growth cones sense a variety of signals in the environment that initiate a variety of intracellular signalling events.
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Growth signals act through the RhoāGTPase signalling pathways to regulate microtublule dynamics that in turn influences the actinomyosin cytoskeleton.
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Once development is complete, axon growth may continue in discrete neurogenic regions of the brain and also following nerve injury.
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Intracellular second messengers such as calcium are important in mediating the response of growth cones to attractive and repulsive cues.
Keywords: growth cone; guidance cues; nerve axon; development; microtubules; actin polymerisation