Graypath/Sandbox | |
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Details | |
Precursor | Glioblast |
Anatomical terminology |
Astrocytes (also known collectively as astroglia) are characteristic star-shaped glial cells in the brain. They perform many functions, including biochemical support of endothelial cells which form the blood-brain barrier, the provision of nutrients to the nervous tissue, and a principal role in the repair and scarring process in the brain.
Astrocytes are a sub-type of the glial cells in the brain. They are also known as astrocytic glial cells. Star-shaped, their many processes envelope synapses made by neurons. Astrocytes are classically identified histologically as many of these cells express the intermediate filament glial fibrillary acidic protein (GFAP). Two forms of astrocytes exist in the CNS, fibrous and protoplasmic. The former is usually located within white matter, have relatively few organelles, and exhibit long unbranched organelles. This type often have "vascular feet" that physically connect the cells to the outside of capillary wall when they are in close proximity of them. The latter, found in grey matter tissue, possess a larger quantity of organelles, and exhibit short and highly branched cellular processes. The two forms of astrocytes when in proximity to the pia mater sends out process to form the pia-glial membrane.
Previously in medical science, the neuronal network was considered the only important one, and astrocytes were looked upon as gap fillers. But recently they have been reconsidered, and are now thought to play a number of active roles in the brain, including the secretion or absorption of neural transmitters and maintenance of the blood-brain barrier.
Furthermore, studies are underway to determine whether astroglia play an instrumental role in depression, based on the link between diabetes and depression. Altered CNS glucose metabolism is seen in both these conditions, and the astroglial cells are the only cells with insulin receptors in the brain.
Astrocytes are linked by gap junctions, creating an electrically coupled syncytium. [4]
An increase in intracellular calcium concentration can propagate outwards through this syncytium. Mechanisms of calcium wave propagation include diffusion of IP3 through gap junctions and extracellular ATP signalling. [5] Calcium elevations are the primary known axis of activation in astrocytes, and are necessary and sufficient for some types of astrocytic glutamate release. [6]
There are several different ways to classify astrocytes:
These have been established by classic work by Raff et al in early 1980s on Rat optic nerves.
Bergmann glia, a type of glia [8] [9] also known as radial epithelial cells (as named by Camillo Golgi), are astrocytes in the cerebellum that have their cell bodies in the Purkinje cell layer and processes that extend into the molecular layer, terminating with bulbous endfeet at the pial surface. Bergmann glia express high densities of glutamate transporters that limit diffusion of the neurotransmitter glutamate during its release from synaptic terminals. Besides their role in early development of the cerebellum, Bergmann glia are also required for the pruning or addition of synapses.
Astrocytomas are primary intracranial tumors derived from astrocytes cells of the brain.
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MUNAnatomy|nerve/neuron}}
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
Graypath/Sandbox | |
---|---|
Details | |
Precursor | Glioblast |
Anatomical terminology |
Astrocytes (also known collectively as astroglia) are characteristic star-shaped glial cells in the brain. They perform many functions, including biochemical support of endothelial cells which form the blood-brain barrier, the provision of nutrients to the nervous tissue, and a principal role in the repair and scarring process in the brain.
Astrocytes are a sub-type of the glial cells in the brain. They are also known as astrocytic glial cells. Star-shaped, their many processes envelope synapses made by neurons. Astrocytes are classically identified histologically as many of these cells express the intermediate filament glial fibrillary acidic protein (GFAP). Two forms of astrocytes exist in the CNS, fibrous and protoplasmic. The former is usually located within white matter, have relatively few organelles, and exhibit long unbranched organelles. This type often have "vascular feet" that physically connect the cells to the outside of capillary wall when they are in close proximity of them. The latter, found in grey matter tissue, possess a larger quantity of organelles, and exhibit short and highly branched cellular processes. The two forms of astrocytes when in proximity to the pia mater sends out process to form the pia-glial membrane.
Previously in medical science, the neuronal network was considered the only important one, and astrocytes were looked upon as gap fillers. But recently they have been reconsidered, and are now thought to play a number of active roles in the brain, including the secretion or absorption of neural transmitters and maintenance of the blood-brain barrier.
Furthermore, studies are underway to determine whether astroglia play an instrumental role in depression, based on the link between diabetes and depression. Altered CNS glucose metabolism is seen in both these conditions, and the astroglial cells are the only cells with insulin receptors in the brain.
Astrocytes are linked by gap junctions, creating an electrically coupled syncytium. [4]
An increase in intracellular calcium concentration can propagate outwards through this syncytium. Mechanisms of calcium wave propagation include diffusion of IP3 through gap junctions and extracellular ATP signalling. [5] Calcium elevations are the primary known axis of activation in astrocytes, and are necessary and sufficient for some types of astrocytic glutamate release. [6]
There are several different ways to classify astrocytes:
These have been established by classic work by Raff et al in early 1980s on Rat optic nerves.
Bergmann glia, a type of glia [8] [9] also known as radial epithelial cells (as named by Camillo Golgi), are astrocytes in the cerebellum that have their cell bodies in the Purkinje cell layer and processes that extend into the molecular layer, terminating with bulbous endfeet at the pial surface. Bergmann glia express high densities of glutamate transporters that limit diffusion of the neurotransmitter glutamate during its release from synaptic terminals. Besides their role in early development of the cerebellum, Bergmann glia are also required for the pruning or addition of synapses.
Astrocytomas are primary intracranial tumors derived from astrocytes cells of the brain.
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)
{{
MUNAnatomy|nerve/neuron}}
{{
cite journal}}
: CS1 maint: multiple names: authors list (
link)