Axon
hideAn axon or nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.
An axon is one of two types of protoplasmic protrusions that extrude from the cell body of a neuron, the other type being dendrites. Axons are distinguished from dendrites by several features, including shape (dendrites often taper while axons usually maintain a constant radius), length (dendrites are restricted to a small region around the cell body while axons can be much longer), and function (dendrites usually receive signals while axons usually transmit them). All of these rules have exceptions, however.
Some types of neurons have no axon—these are called amacrine cells, and transmit signals from their dendrites. No neuron ever has more than one axon; however in invertebrates such as insects the axon sometimes consists of several regions that function more or less independently of each other. Most axons branch, in some cases very profusely.
Axons make contact with other cells—usually other neurons but sometimes muscle or gland cells—at junctions called synapses. At a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. Some synaptic junctions appear partway along an axon as it extends—these are called en passant ("in passing") synapses. Other synapses appear as terminals at the ends of axonal branches. A single axon, with all its branches taken together, can innervate multiple parts of the brain and generate thousands of synaptic terminals.
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News tagged with axons
RNA on the move
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In the fruit fly Drosophila, oskar mRNA, which is involved in defining the animal’s body axes, is produced in the nuclei of nurse cells neighbouring the oocyte, and must be transported to the oocyte and along ...
Researchers to develop probes to study cellular GPS
Nov 10, 2009 |
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An international group of researchers from Carnegie Mellon University, Goettingen Medical School in Germany and the University of Cambridge in the United Kingdom have received a Human Frontiers Science Program (HFSP) grant ...
Regeneration can be achieved after chronic spinal cord injury
Medicine & Health / Neuroscience
Oct 28, 2009 |
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Scientists at the University of California, San Diego School of Medicine report that regeneration of central nervous system axons can be achieved in rats even when treatment delayed is more than a year after the original ...
Damaging inflammatory response could hinder spinal cord repair
Medicine & Health / Neuroscience
Oct 21, 2009 |
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(PhysOrg.com) -- The inflammatory response following a spinal cord injury appears to be set up to cause extra tissue damage instead of promoting healing, new research suggests.
Rethinking Alzheimer's disease and its treatment targets
Medicine & Health / Neuroscience
Sep 22, 2009 |
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(PhysOrg.com) -- Psychiatry professor George Bartzokis introduces a new theory about the fundamental cause of Alzheimer's and other neurodegenerative diseases.
Researchers discover molecule responsible for axonal branching
Sep 21, 2009 |
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The human brain consists of about 100 billion (1011) neurons, which altogether form about 100 trillion (1014) synaptic connections with each other. A crucial mechanism for the generation of this complex wiring pattern is ...
Neurons found to be similar to Electoral College
Medicine & Health / Neuroscience
Sep 14, 2009 |
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A tiny neuron is a very complicated structure. Its complex network of dendrites, axons and synapses is constantly dealing with information, deciding whether or not to send a nerve impulse, to drive a certain action.
Tension in axons is essential for synaptic signaling, researchers report
Jul 20, 2009 |
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Every time a neuron sends a signal - to move a muscle or form a memory, for example - tiny membrane-bound compartments, called vesicles, dump neurotransmitters into the synapse between the cells. Researchers ...
Researchers regenerate axons necessary for voluntary movement
Apr 06, 2009 |
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For the first time, researchers have clearly shown regeneration of a critical type of nerve fiber that travels between the brain and the spinal cord and which is required for voluntary movement. The regeneration was accomplished ...
Lab-grown nerves promote nerve regeneration after injury
Mar 19, 2009 |
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Researchers at the University of Pennsylvania School of Medicine have engineered transplantable living nerve tissue that encourages and guides regeneration in an animal model. Results were published this month in Tissue En ...
Study gives more proof that intelligence is largely inherited
Medicine & Health / Neuroscience
Mar 17, 2009 |
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They say a picture tells a thousand stories, but can it also tell how smart you are? Actually, say UCLA researchers, it can.
Scientists discover master regulator of motor neuron firing
Medicine & Health / Neuroscience
Mar 16, 2009 |
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(PhysOrg.com) -- When the Human Genome Project was complete, DNA bowed out of the limelight and gave way to RNA as a major player in genetic regulation. Now, findings at Rockefeller University mirror this ...
Blocking protein may help ease painful nerve condition
Medicine & Health / Neuroscience
Mar 15, 2009 |
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Scientists have identified the first gene that pulls the plug on ailing nerve cell branches from within the nerve cell, possibly helping to trigger the painful condition known as neuropathy.
Experts examine causes, treatment and prevention of glaucoma
Mar 04, 2009 |
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Although scientists know progressive degeneration of retinal ganglion cells and their axons is the primary cause of glaucoma, researchers have yet to identify a way to stop or prevent the degeneration.
Rett Syndrome scientist makes significant discovery
Feb 23, 2009 |
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A paper published online today in Nature Neuroscience reveals the presence of methyl CpG binding protein 2 (MeCP2) in glia. MeCP2 is a protein associated with a variety of neurological disorders, including Rett Syndrome, the mo ...
