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Dorsal root ganglion
	This is a dorsal root ganglion (DRG) from a chicken embryo (around stage of day 7) after incubation overnight in NGF growth medium stained with anti-neurofilament antibody. Axons growing out of the ganglion are visible.
	A spinal nerve with its anterior and posterior roots. The dorsal root ganglion is the "spinal ganglion", following the posterior/dorsal root.
Latin	ganglion sensorium nervi spinalis
Gray's	subject #185 750
Precursor	neural crest
MeSH	Spinal+Ganglia

In anatomy and neurology, a dorsal root ganglion (or spinal ganglion) is a nodule on a dorsal root that contains cell bodies of neurons in afferent spinal nerves.

[edit] Unique unipolar structure

The axons of dorsal root ganglion neurons are known as afferents. In the peripheral nervous system, afferents refer to the axons that relay sensory information into the central nervous system and spinal cord. These neurons are of the pseudo-unipolar type, meaning they have an axon with two branches that act as a single axon, often referred to as a distal process and a proximal process.

Note: the neuron is parted of two parts:

1- Dendrite that receives the information and sends it to the Perykaron (cytoplasm which is around the nucleus)

2- Axon: which takes this information and sends forward

in the pseudo-unipolar one receives information and one sends forward, so sometime they are called a dendrite and an axon, even though the dendrite this time is covered with Myelin!

Unlike the majority of neurons found in the central nervous system, an action potential in dorsal root ganglion neuron may initiate in the distal process in the periphery, bypass the cell body, and continue to propagate along the proximal process until reaching the synaptic terminal in the dorsal horn of the spinal cord.

[edit] Distal section

The distal section of the axon may either be a bare nerve ending or encapsulated by a structure that helps relay specific information to nerve. For example, a Meissner's corpuscle or Pacinian corpuscle may encapsulate the nerve ending, rendering the distal process sensitive to mechanical stimulation, such as stroking or vibration, respectively. ^[1]

[edit] Location

The dorsal root ganglia lie along the vertebral column by the spine.

[edit] Embryology

The dorsal root ganglia develops in the embryo from neural crest cells.

[edit] Nociception

Proton-sensing G protein-coupled receptors are expressed by DRG sensory neurons and might play a role in acid-induced nociception.^[2]

[edit] References

^ Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed., p.431-433. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6
^ Huang CW, Tzeng JN, Chen YJ, Tsai WF, Chen CC, Sun WH (2007). "Nociceptors of dorsal root ganglion express proton-sensing G-protein-coupled receptors". Mol. Cell. Neurosci. 36 (2): 195–210. doi:10.1016/j.mcn.2007.06.010. PMID 17720533.

[edit] See also

Ventral root

[edit] Additional images

Medulla spinalis

The formation of the spinal nerve from the dorsal and ventral roots |

Scheme showing structure of a typical spinal nerve.

[edit] External links

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[0] Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed., p.431-433. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6

[pmid17720533-1] Huang CW, Tzeng JN, Chen YJ, Tsai WF, Chen CC, Sun WH (2007). "Nociceptors of dorsal root ganglion express proton-sensing G-protein-coupled receptors". Mol. Cell. Neurosci. 36 (2): 195–210. doi:10.1016/j.mcn.2007.06.010. PMID 17720533.

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