Neurite

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Scheme of a multipolar nerve cell with several dendrites and a neurite encased by glial cells (here Schwann cells ) as an axon in a myelin sheath .

The term neurite can be used in German for different terms, with the efferent cell process of a neuron being included in the scope of the term in each case .

The underlying term neurite encompasses the only extension of a neuron with which it can transmit excitation away from the cell body (efferent) to selected cells, regardless of whether this nerve cell extension runs in an envelope or not. When enveloped by glial cells , a neurite is also referred to as an axis cylinder or axon ; The axon plus the glial sheath together form a nerve fiber . An axon is called myelinated when this sheath is designed as a myelin sheath , as is the case with myelinated nerve fibers. Since the vast majority of neurites are enveloped by glia, the terms neurite and axon can be used almost synonymously.

The neurite emerges at the cone of origin (axon hill) from the area of ​​the cell body ( soma ) of a neuron called the perikaryon , can give off side branches as collaterals and branch out with an end tree ( telodendron ) into several presynaptic endings (axon terminals). In addition to the neurite, multipolar, bipolar and pseudounipolar neurons have cell processes that are differentiated as dendrites .

In the case of bipolar nerve cells , their two processes can also be referred to as the dendritic axon or neuritic axon. In the case of pseudounipolar nerve cells , the term neurite is often used more broadly for both (similarly structured and glial-covered) processes or extensions; in the neurons of the sensitive cranial nerve and spinal ganglia , these are often also called peripheral or central neurites. In this case the peripheral branch - corresponding to the dendritic one of a bipolar nerve cell - is sometimes significantly longer than the central neurite.

Furthermore, neurite also stands for sprouting processes of developing neurons of the neuroepithelium or hair-like cell processes of neurons in cell cultures . These processes can later differentiate or regress. In this sense, the term neurite can occasionally be understood as an umbrella term for nerve cell processes.

Individual evidence

  1. ↑ a b H. Leonhardt: Histology, Cytology and Microanatomy of Humans. Thieme Verlag, 1981, ISBN 3-13-371506-2 , pp. 209ff.
  2. ↑ F. Wachtler: Histology: textbook of cytology, histology and microscopic human anatomy. Verlag Maudrich, 2005, ISBN 3-85076-681-0 , p. 188 ( limited preview in Google book search).
  3. ↑ Th. Heinzeller, C. Büsing: Histology, Histopathology and Cytology for an introduction. Thieme Verlag, 2001, ISBN 3-13-126831-X , p. 61ff ( limited preview in Google book search).
  4. ↑ Renate Lüllmann-Rauch: Pocket textbook histology. 3. Edition. Thieme Verlag, 2009, ISBN 978-3-13-129243-8 , pp. 174f ( limited preview in Google book search).
  5. ^ RF Schmidt: Outline of Neurophysiology. 2nd Edition. Springer, Berlin / Heidelberg / New York 1972, ISBN 3-540-06022-7 , p. 3.
  6. ↑ Benninghoff: Macroscopic and microscopic anatomy of humans, volume 3. Nervous system, skin and sensory organs. Verlag Urban & Schwarzenberg, 1985, ISBN 3-541-00264-6 , p. 4.
  7. ↑ Benninghoff: Macroscopic and microscopic anatomy of humans, volume 3. Nervous system, skin and sensory organs. Verlag Urban & Schwarzenberg, 1985, ISBN 3-541-00264-6 , p. 5.
  8. ↑ Werner Linß, Jochen Fanghänel (Ed.): Histology. Walter de Gruyter, 1999, p. 265 ( limited preview in the Google book search).
  9. ↑ Renate Lüllmann-Rauch: Pocket textbook histology. 3. Edition. Thieme Verlag, 2009, ISBN 978-3-13-129243-8 , p. 208 ( limited preview in Google book search).
  10. ^ Website of the National Center for Biotechnology (NCBI), search term "Neurites" - MeSH. Retrieved March 24, 2013 .