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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/05/06 21:50:40」(JST)

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The soma (pl. somata or somas), or perikaryon (pl. perikarya), or cyton, is the bulbous end of a neuron, containing the cell nucleus. The word "soma" comes from the Greek σῶμα, meaning "body"; the soma of a neuron is often called the "cell body". There are many different specialized types of neurons, and their sizes vary from as small as about 5 micrometres to over 10 millimetre for some of the smallest and largest neurons of invertebrates, respectively.

The soma (main part of the neuron in which the dendrites branch off of) contains many organelles, including granules called Nissl granules, which are composed largely of rough endoplasmic reticulum and free polyribosomes.^[1] The cell nucleus is a key feature of the soma. The nucleus is the source of most of the RNA that is produced in neurons. In general, most proteins are produced from mRNAs that do not travel far from the cell nucleus. This creates a challenge for supplying new proteins to axon endings that can be a meter or more away from the soma. Axons contain microtubule-associated motor proteins that transport protein-containing vesicles between the soma and the synapses at the axon terminals. Such transport of molecules towards and away from the soma maintains critical cell functions.

The axon hillock is a specialized domain of the neuronal cell body from which the axon originates. A high amount of protein synthesis occurs in this region, as it contains a large number of Nissl granules (which are ribosomes wrapped in RER) and polyribosomes. Within the axon hillock, materials are sorted as either items that will enter the axon (like the components of the cytoskeletal architecture of the axon, mitochondria, etc.) or will remain in the soma. In addition, the axon hillock also has a specialized plasma membrane that contains large numbers of voltage-gated ion channels, since this is most often the site of action potential initiation.^[1]

The survival of some sensory neurons depends on axon terminals making contact with sources of survival factors that prevent apoptosis. The survival factors are neurotrophic factors, including molecules such as nerve growth factor (NGF). NGF interacts with receptors at axon terminals, and this produces a signal that must be transported up the length of the axon to the nucleus. A current theory of how such survival signals are sent from axon endings to the soma includes the idea that NGF receptors are endocytosed from the surface of axon tips and that such endocytotic vesicles are transported up the axon.^[2]

References

^ ^a ^b Squire, Larry; Berg, Darwin; Bloom, Floyd; du Lac, Sascha; Ghosh, Anirvan; Spitzer, Nicholas, eds. (2008). Fundamental Neuroscience (3rd ed.). Academic Press. ISBN 978-0-12-374019-9.
^ Delcroix JD, Valletta J, Wu C, et al. (2004). "Trafficking the NGF signal: implications for normal and degenerating neurons". Prog. Brain Res. 146: 3–23. PMID 14699953.

External links

Histology at OU 3_09 - "Slide 3 Spinal cord"

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1. アレキサンダー病 alexander disease

English Journal

Status epilepticus stimulates NDEL1 expression via the CREB/CRE pathway in the adult mouse brain.

Choi YS1, Lee B2, Hansen KF3, Aten S3, Horning P3, Wheaton KL4, Impey S5, Hoyt KR4, Obrietan K6.
Neuroscience.Neuroscience.2016 Sep 7;331:1-12. doi: 10.1016/j.neuroscience.2016.06.010. Epub 2016 Jun 11.
Nuclear distribution element-like 1 (NDEL1/NUDEL) is a mammalian homolog of the Aspergillus nidulans nuclear distribution molecule NudE. NDEL1 plays a critical role in neuronal migration, neurite outgrowth and neuronal positioning during brain development; however within the adult central nervous sy
PMID 27298008

Morphological and antioxidant impairments in the spinal cord of male offspring rats following exposure to a continuous 900MHz electromagnetic field during early and mid-adolescence.

İkinci A1, Mercantepe T2, Unal D3, Erol HS4, Şahin A5, Aslan A5, Baş O6, Erdem H7, Sönmez OF8, Kaya H9, Odacı E10.
Journal of chemical neuroanatomy.J Chem Neuroanat.2016 Sep;75(Pt B):99-104. doi: 10.1016/j.jchemneu.2015.11.006. Epub 2015 Dec 17.
The effects of devices emitting electromagnetic field (EMF) on human health have become the subject of intense research among scientists due to the rapid increase in their use. Children and adolescents are particularly attracted to the use of devices emitting EMF, such as mobile phones. The aim of t
PMID 26708410

Localization of the M2 muscarinic cholinergic receptor in dendrites, cholinergic terminals, and noncholinergic terminals in the rat basolateral amygdala: An ultrastructural analysis.

Muller JF1, Mascagni F1, Zaric V1, Mott DD1, McDonald AJ1.
The Journal of comparative neurology.J Comp Neurol.2016 Aug 15;524(12):2400-17. doi: 10.1002/cne.23959. Epub 2016 Feb 8.
Activation of M2 muscarinic receptors (M2Rs) in the rat anterior basolateral nucleus (BLa) is critical for the consolidation of memories of emotionally arousing events. The present investigation used immunocytochemistry at the electron microscopic level to determine which structures in the BLa expre
PMID 26779591

Japanese Journal

Projections of nucleus accumbens adenosine A2A receptor neurons in the mouse brain and their implications in mediating sleep-wake regulation

Zhang Jian-Ping,Xu Qi,Yuan Xiang-Shan,Cherasse Yoan,Schiffmann Serge N.,de Kerchove d'Exaerde Alban,Qu Wei-Min,Urade Yoshihiro,Lazarus Michael,Huang Zhi-Li,Li Rui-Xi
Frontiers in Neuroanatomy 7, 43, 2013-12
… Immunohistochemistry was then used to visualize hrGFP highlighting the perikarya of the A(2A)R neurons in the injection sites, and their axons in projection regions. … The data revealed that A(2A)R neurons exhibit medium-sized and either round or elliptic perikarya with their processes within the Acb. …
NAID 120005367979

Ultrastructural Study on Colocalization of Glucagon-Like Peptide (GLP)-1 with GLP-2 in Chicken Intestinal L-Cells

Nishimura Kei,Hiramatsu Kohzy,Monir Mohammad M.,Takemoto Chihiro,Watanabe Takafumi
JOURNAL OF VETERINARY MEDICAL SCIENCE 75(10), 1335-1339, 2013-10
… Transmission electron microscopy indicated that L-cells identified by colloidal gold-labeled immunocytochemistry were covered apically with microvilli, open-type and contained many secretory granules in their perikarya. …
NAID 120005468444

Ultrastructural Study on Colocalization of Glucagon-Like Peptide (GLP)-1 with GLP-2 in Chicken Intestinal L-Cells

NISHIMURA Kei,HIRAMATSU Kohzy,MONIR Mohammad M. [他],TAKEMOTO Chihiro,WATANABE Takafumi
Journal of Veterinary Medical Science 75(10), 1335-1339, 2013
… Transmission electron microscopy indicated that L-cells identified by colloidal gold-labeled immunocytochemistry were covered apically with microvilli, open-type and contained many secretory granules in their perikarya. …
NAID 130003362229