Term
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Definition
| After the cell body migrates to the appropriate layer, the axon extends, sometimes for long long stretches. |
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Term
| Pathfinder/pioneer neurons |
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Definition
| Early in development an axon must find its path... Later, once sevearl axons have extended to their targets, other growin axons can simply 'hitch a ride' |
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Term
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Definition
Cells that axons can utilize as guide for their growth. Eliminating these guiding cells detrimentally affects the ability of the axon to find the appropriate target.
(i.e. grasshoper leg)
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Term
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Definition
| Area heading the neurite that is dynamic in receptors, shape and structure. Specially designed to achieve appropriate axonal growth. |
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Definition
| Bundle of axons on which a growth cone can adhere to and grow. |
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Term
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Definition
| "Skeletal" system of the cell. Principally composed of microtubulues, actin and intermediate fibers. These provide structure, movement, transportation of materials...etc. and are crucial, dynamic components of the growth cone |
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Term
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Definition
| Large (25nm diameter) and extend along the axon to allow transpor tof materials in the cell. |
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Term
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Definition
Small (7nm diameter) and provide function to dynamic behavior of the growth cone (particularly filopedia).
Provides pulling functions of growth cone with myosin anchors. |
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Term
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Definition
| Medium (10nm in diameter) provide structural support |
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Term
| Actin depolymerizing agent |
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Definition
Drugs such as cytochalasin that block actin mediated functions by inhibiting the polymerization fo actin. Effects include prevention of growth cones from reaching targets.
Due to these depolymerizing effects, will induce turning of axon to other side. |
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Term
| Microtubulue polymerization |
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Definition
| Microtubule polymerization is also crucial to axonal growth since as the axon growth more microtubules are added internally and these carry membrane that is added to the growing axon at the base of the growth axon. |
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Term
| Microtubule Associate Proteins |
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Definition
MAPs are found in growing neurites and regulate neuronal growth
(e.g. MAP2 and Tau) |
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Term
| Actin Associated Proteins |
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Definition
Also invovled in axonal growth by regulating actin.
The important part of these and MAPs is that they maintain dynamicism of the cytoskeleton because if they stablize it too much, changes cannot be made and and growth is retarded. |
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Term
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Definition
Growth is promoted in adhesive surfaces, however can't be too "sticky" because then stuck.
ECM proteins can provide some fo that adhesion
Depending on cell surface composition, neurons have "preferred" adhesive proteins
Integrin, different subunits. |
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Term
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Definition
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Term
| Contact Adhesion/repulsion |
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Definition
Cues that direct growth cones along with long rante attraction/repulsion
???? |
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Term
Homophilic v Heterophilic molecules
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Definition
Cell surface molecules that mediate adhesion. Heterophilic molecules are attraction between 2 different type of molecules while homophilic is attraction to the same type fo moelcule....
Cadherins are homophillic while CAMs can be both |
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Term
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Definition
| Neuronal Cell Adhesion Molecules, generated by neurons and glia. |
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Term
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Definition
| Sialylated NCAM is not sticky... Non-sialylated (by Endo-N) is sticky. |
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Term
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Definition
Finding pathways by avoiding some routes... Release of factors.
(e.g. septum or ventral spinal cord) |
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Term
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Definition
Chemorepulsive signal that causes growth cone to collapse.
Thus chemoattractants and chemorepulsives are coordinately utelized to guide axonal growth |
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Term
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Definition
Guide for axonal growth could also be due to increase in gradient which is the case of netrins that are released by floorplate of neural tube and are chemoattractant.
Also example of how the same signal can attract or repel depending on envrionment since low cAMP, netrin is repulsive. |
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