Microglia

Abstract

Microglia are resident brain macrophages that respond to even minor pathological events in the central nervous system. Microglia phagocytose debris, present antigens to T cells and contribute to brain damage by production of neurotoxic factors.

Keywords: microglia; macrophages; Wallerian degeneration; inflammation; nervous system

Figure 1.

Morphological transition of rat microglia during activation. Microglia were stained by immunocytochemistry with an antibody against the complement receptor 3. (a) Typical morphology of ramified microglia in the normal brain. As an early response to brain damage (e.g. ischaemia), microglia retract processes and round up (arrows in (b)). This is followed by transition into phagocytic microglia as shown in (c; open arrows) and (d). Note enlargement of the cell bodies in (d) compared to (a). (c) Typical appearance of activated microglia in degenerating fibre tracts of the CNS (arrows). Scale bar=20 μm. Reproduced from Schroeter et al. with permission of the American Heart Association.

Figure 2.

Surface and activation markers of rat microglia. Ramified microglia of the hippocampus (a) and normal spinal cord (b,c) expressing a microglia‐specific surface keratan sulfate proteoglycan (a,b) and major histocompatibility complex type 2 molecules (c; arrow). Note staining of the cellular processes typical for ramified microglia (arrow in (b)). After transection of a fibre tract in the CNS (optic nerve) microglia are activated and express the lysosomal antigen ED1 (d), indicating their transformation into phagocytes, and the surface molecule CD4 (e). Scale bars in (a) =200 μm; (b, c) = 40 μm; (d, e) = 300 μm.

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References

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Further Reading

Becher B, Prat A and Antel JP (2000) Brain‐immune connection: immuno‐regulatory properties of CNS‐resident cells. Glia 29: 293–304.

Federoff S (1995) Development of microglia. In: Kettenmann H and Ransom BR (eds) Neuroglia, pp. 162–181. Oxford: Oxford University Press.

Goodrum JF and Bouldin TW (1996) The cell biology of myelin degeneration and regeneration in the peripheral nervous system. Journal of Neuropathology and Experimental Neurology 55: 943–953.

Guilian D (1995) Microglia and neuronal dysfunction. In: Kettenmann H and Ransom BR (eds) Neuroglia, pp. 671–684. Oxford: Oxford University Press.

Kreutzberg G (1996) Microglia: a sensor for pathological events in the CNS. Trends in Neuroscience 19: 312–318.

Ling EA and Wong WC (1993) The origin and nature of ramified and amoeboid microglia: a historical review and current concepts. Glia 7: 9–18.

Perry VH, Andersson PB and Gordon S (1993) Macrophages and inflammation in the central nervous system. Trends in Neuroscience 16: 268–273.

del Rio Hortega P (1932) Microglia. In: Penfield W (ed.) Cytology and Cellular Pathology of the Nervous System, vol. 2, pp. 481–534. New York: PB Hoeber.

Schwab M (1990) Myelin‐associated inhibitors of neurite growth and regeneration in the CNS. Trends in Neuroscience 13: 452–456.

Stoll G, Jander S and Schroeter M (1998) Inflammation and glial responses in ischemic brain lesions. Progress in Neurobiology 56: 149–171.

Stoll G and Jander S (1999) The role of microglia and macrophages in the pathophysiology of the CNS. Progress in Neurobiology 58: 233–247.

Streit WJ (1995) Microglial cells. In: Kettenmann H and Ransom BR (eds) Neuroglia, pp. 85–96. Oxford: Oxford University Press.

Streit WJ (2002) Microglia as neuroprotective, immunocompetent cells of the CNS. Glia 40: 133–139.

Wekerle H (1995) Antigen presentation by central nervous system glia. In: Kettenmann H and Ransom BR (eds) Neuroglia, pp. 685–699. Oxford: Oxford University Press.

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Stoll, Guido, and Jander, Sebastian(Sep 2005) Microglia. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0004086]