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Astrocyte
Astrocytes (from Ancient Greek , , "star" and , , "cavity", "cell"), also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord. They perform many functions, including biochemical control of endothelial cells that form the blood–brain barrier, provision of nutrients to the nervous tissue, maintenance of extracellular ion balance, regulation of cerebral blood flow, and a role in the repair and scarring process of the brain and spinal cord following infection and traumatic injuries. The proportion of astrocytes in the brain is not well defined; depending on the counting technique used, studies have found that the astrocyte proportion varies by region and ranges from 20% to around 40% of all glia. Another study reports that astrocytes are the most numerous cell type in the brain. Astrocytes are the major source of cholesterol in the central nervous system. Apolipoprotein E transports cholesterol from astrocytes to neurons and ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glial Scar
A glial scar formation (gliosis) is a reactive cellular process involving astrogliosis that occurs after injury to the central nervous system. As with scarring in other organs and tissues, the glial scar is the body's mechanism to protect and begin the healing process in the nervous system. In the context of neurodegeneration, formation of the glial scar has been shown to have both beneficial and detrimental effects. Particularly, many neuro-developmental Enzyme inhibitor, inhibitor molecules are secreted by the cells within the scar that prevent complete physical and functional recovery of the central nervous system after injury or disease. On the other hand, absence of the glial scar has been associated with impairments in the repair of the blood brain barrier. Scar components The glial scar is composed of several components briefly discussed below. Reactive astrocytes Reactive astrocytes are the main cellular component of the glial scar. After injury, astrocytes undergo morph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliotransmitter
Gliotransmitters are chemicals released from glial cells that facilitate communication between glial cells and neurons. They are usually induced from Ca2+ signaling, although recent research has questioned the role of Ca2+ in gliotransmitters and may require a revision of the relevance of gliotransmitters in neuronal signalling in general. While gliotransmitters can be released from any glial cell, they are primarily released from astrocytes. Astrocytes rely on gap junctions for coupling, and are star-like in shape, which allows them to come into contact with many other synapses in various regions of the brain. Their structure also makes them capable of bidirectional signaling. It is estimated that astrocytes can make contact with over 100,000 synapses, allowing them to play an essential role in synaptic transmission. While gliotransmission primarily occurs between astrocytes and neurons, gliotransmission is not limited to these two cell types. Besides the central nervous system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glial Cells
Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (the brain and the spinal cord) and in the peripheral nervous system that do not produce electrical impulses. The neuroglia make up more than one half the volume of neural tissue in the human body. They maintain homeostasis, form myelin, and provide support and protection for neurons. In the central nervous system, glial cells include oligodendrocytes (that produce myelin), astrocytes, ependymal cells and microglia, and in the peripheral nervous system they include Schwann cells (that produce myelin), and satellite cells. Function They have four main functions: * to surround neurons and hold them in place * to supply nutrients and oxygen to neurons * to insulate one neuron from another * to destroy pathogens and remove dead neurons. They also play a role in neurotransmission and synaptic connections, and in physiological processes such as breathing. While glia wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glial Fibrillary Acidic Protein
Glial fibrillary acidic protein (GFAP) is a protein that is encoded by the ''GFAP'' gene in humans. It is a type III intermediate filament (IF) protein that is expressed by numerous cell types of the central nervous system (CNS), including astrocytes and ependymal cells during development. GFAP has also been found to be expressed in glomeruli and peritubular fibroblasts taken from rat kidneys, Leydig cells of the testis in both hamsters and humans, human keratinocytes, human osteocytes and chondrocytes and stellate cells of the pancreas and liver in rats. GFAP is closely related to the other three non- epithelial type III IF family members, vimentin, desmin and peripherin, which are all involved in the structure and function of the cell's cytoskeleton. GFAP is thought to help to maintain astrocyte mechanical strength as well as the shape of cells, but its exact function remains poorly understood, despite the number of studies using it as a cell marker. The protein wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radial Glial Cell
Radial glial cells, or radial glial progenitor cells (RGPs), are Bipolar neuron, bipolar-shaped progenitor cells that are responsible for producing all of the neurons in the cerebral cortex. RGPs also produce certain lineages of glia, including astrocytes and oligodendrocytes. Their Cell body, cell bodies (somata) reside in the embryonic ventricular zone, which lies next to the developing ventricular system. During development, neuroblast, newborn neurons use radial glia as scaffolds, traveling along the radial glial fibers in order to reach their final destinations. Despite the various possible fates of the radial glial population, it has been demonstrated through Cell lineage#Fate mapping techniques, clonal analysis that most radial glia have restricted, Cell potency#unipotency, unipotent or Cell potency#multipotency, multipotent, fates. Radial glia can be found during the Neurogenesis, neurogenic phase in all vertebrates (studied to date). The term "radial glia" refers to the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glioblast
A glioblast is a type of cell located in the embryonic neuroectoderm that has the ability to differentiate into several different types of neuroglia through asymmetric cell division. It comes from a precursor ( spongioblast). However, the latter may also differentiate into an ependymoblast. Glioblasts differentiate into astrocytes and oligodendrocytes. Its tumor is called a glioblastoma, and is the most common type of central nervous system malignancy. See also * Glioblastoma multiforme * List of human cell types derived from the germ layers This is a list of Cell (biology), cells in humans derived from the three embryonic germ layers – ectoderm, mesoderm, and endoderm. Cells derived from ectoderm Surface ectoderm Skin * Trichocyte (human), Trichocyte * Keratinocyte Anterior pi ... References * Embryology of nervous system {{developmental-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood–brain Barrier
The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system, thus protecting the brain from harmful or unwanted substances in the blood. The blood–brain barrier is formed by endothelial cells of the Capillary, capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane. This system allows the passage of some small molecules by passive transport, passive diffusion, as well as the selective and active transport of various nutrients, ions, organic anions, and macromolecules such as glucose and amino acids that are crucial to neural function. The blood–brain barrier restricts the passage of pathogens, the diffusion of solutes in the blood, and Molecular mass, large or Hydrophile, hydrophilic molecules into the cerebrospinal fluid, while a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apolipoprotein E
Apolipoprotein E (Apo-E) is a protein involved in the metabolism of fats in the body of mammals. A subtype is implicated in Alzheimer's disease and cardiovascular diseases. It is encoded in humans by the gene ''APOE''. Apo-E belongs to a family of fat-binding proteins called apolipoproteins. In the circulation, it is present as part of several classes of lipoprotein particles, including chylomicron remnants, VLDL, IDL, and some HDL. Apo-E interacts significantly with the low-density lipoprotein receptor (LDLR), which is essential for the normal processing (catabolism) of triglyceride-rich lipoproteins. In peripheral tissues, Apo-E is primarily produced by the liver and macrophages, and mediates cholesterol metabolism. In the central nervous system, Apo-E is mainly produced by astrocytes and transports cholesterol to neurons via Apo-E receptors, which are members of the low density lipoprotein receptor gene family. Apo-E is the principal cholesterol carrier in the brain. Apo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pia Mater
Pia mater ( or ),Entry "pia mater" in Merriam-Webster Online Dictionary ', retrieved 2012-07-28. often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the and . ''Pia mater'' is medieval Latin meaning "tender mother". The other two meningeal membranes are the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermediate Filaments
Intermediate filaments (IFs) are cytoskeletal structural components found in the cells of vertebrates, and many invertebrates. Homologues of the IF protein have been noted in an invertebrate, the cephalochordate ''Branchiostoma''. Intermediate filaments are composed of a family of related proteins sharing common structural and sequence features. Initially designated 'intermediate' because their average diameter (10 nm) is between those of narrower microfilaments (actin) and wider myosin filaments found in muscle cells, the diameter of intermediate filaments is now commonly compared to actin microfilaments (7 nm) and microtubules (25 nm). Animal intermediate filaments are subcategorized into six types based on similarities in amino acid sequence and protein structure. Most types are cytoplasmic, but one type, Type V is a nuclear lamin. Unlike microtubules, IF distribution in cells shows no good correlation with the distribution of either mitochondria or endop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapses
In the nervous system, a synapse is a structure that allows a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or a target effector cell. Synapses can be classified as either chemical or electrical, depending on the mechanism of signal transmission between neurons. In the case of electrical synapses, neurons are coupled bidirectionally with each other through gap junctions and have a connected cytoplasmic milieu. These types of synapses are known to produce synchronous network activity in the brain, but can also result in complicated, chaotic network level dynamics. Therefore, signal directionality cannot always be defined across electrical synapses. Chemical synapses, on the other hand, communicate through neurotransmitters released from the presynaptic neuron into the synaptic cleft. Upon release, these neurotransmitters bind to specific receptors on the postsynaptic membrane, inducing an electrical or chemical response in the target neuron. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vimentin
Vimentin is a structural protein that in humans is encoded by the ''VIM'' gene. Its name comes from the Latin ''vimentum'' which refers to an array of flexible rods. Vimentin is a Intermediate filament#Type III, type III intermediate filament (IF) protein that is expressed in mesenchymal cells. Intermediate filament, IF proteins are found in all Animal, animal cells as well as bacteria. Intermediate filaments, along with tubulin-based microtubules and actin-based microfilaments, comprise the cytoskeleton. All IF proteins are expressed in a highly developmentally-regulated fashion; vimentin is the major cytoskeletal component of mesenchymal cells. Because of this, vimentin is often used as a marker of mesenchymally-derived cells or cells undergoing an Epithelial-mesenchymal transition, epithelial-to-mesenchymal transition (EMT) during both normal development and Metastasis, metastatic progression. Structure The assembly of the fibrous vimentin filament that forms the cytosk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
