Cells of the Nervous System


The principal and distinct classes of the nervous system are nerve cells (neurons) and neuroglial cells (glia). They can be divided into different cell classes according to their structure and the basic mechanisms they use to communicate.

Keywords: neuron; glia; axon; dendrite; synapse; blood vessels

Figure 1.

Schematic representation of a pyramidal neuron with an astrocyte and oligodendrocyte in close proximity. The astrocyte has an endfoot formed around the capillary endothelial cells and some of its other processes are in close association with the dendrites of the neuron. The oligodendrocyte is myelinating the axon immediately distal to the axon hillock. Axonal boutons are also shown synapsing on the apical dendrite (circled). This portion of the diagram is enlarged in Figure .

Figure 2.

Light micrographs of a pyramidal neuron (left) and an interneuron (right) stained using the Golgi silver technique. The interneuron is photographed at a higher magnification to show the large number of spines arranged along its dendrites (marked with small black arrow). Also indicated is the axon emerging from the cell body (large black arrow). The scale bar in the left‐hand micrograph is 50 μm and in the right, 20 μm.

Figure 3.

Schematic representation of two forms of synapse, one formed between an axon's bouton and a dendritic spine, the other between a bouton and the dendrite's shaft. Note the vesicles within the presynaptic terminal close to the synapse.

Figure 5.

Schematic representation of a chemical synapse, showing the movement of calcium ions through voltage‐gated calcium channels, causing neurotransmitter‐containing vesicles to bind to the presynaptic membrane and releasing molecules into the synaptic cleft. These molecules are able to diffuse across the gap and bind to receptors in the postsynaptic membrane. Ligand‐gated (fast) receptors are shown in which the movement of ions takes place across the receptor itself once the neurotransmitter attaches to its binding site.

Figure 4.

Electron micrograph showing synapses (indicated with arrows) within the cerebral cortex situated on dendrites (dt) and their spines (sp). Notice the aggregation of vesicles in the cytoplasm of the presynaptic terminal. Mitochondria are also indicated (m). The scale bar represents 0.5 μm.


Further Reading

Kandel ER, Schwartz JH and Jessell TM (2000) Principles of Neural Science, 4th edn. New York: McGraw‐Hill.

Levitan IB and Kaczmarek LK (1997) The Neuron, Cell and Molecular Biology, 2nd edn. New York: Oxford University Press.

Nicholls JG, Martin AR and Wallace BG (1992) From Neuron to Brain, 3rd edn. Sunderland, MA: Sinauer Associates.

Peters A, Palay SL and Webster HF (1976) The Fine Structure of the Nervous System: The Neurons and Supporting Cells. London: WB Saunders.

Shepherd GM (1994) Neurobiology, 3rd edn. New York: Oxford University Press.

Zigmond MJ, Bloom FE, Landis SC, Roberts JL and Squire LR (1999) Fundamental Neuroscience. New York: Academic Press.

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Knott, Graham, and Molnar, Zoltan(Apr 2001) Cells of the Nervous System. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0000031]