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ependyma
Ependyma is the thin epithelium-like lining of the ventricular system of the brain and the central canal of the spinal cord. Ependyma is one of the four types of neuroglia in the central nervous system (CNS). It is involved in the production of cerebrospinal fluid (CSF).
==Ependymal cells==
The ependyma is made up of ependymal cells (ependymocytes), a type of glial cell. These cells line the CSF-filled ventricles in the brain and the central canal of the spinal cord. The cells are ciliated simple columnar〔Hitsology, a text in atlas, M. Ross 2011, 6th edition page 367〕 epithelium-like cells. Their apical surfaces are covered in a layer of cilia, which circulate CSF around the CNS. Their apical surfaces are also covered with microvilli, which absorb CSF. Ependymal cells also produce CSF. Within the ventricles of the brain, a population of modified ependymal cells and capillaries together form a system called the choroid plexus, which produces the CSF.
Modified tight junctions between ependymal cells control fluid release across the epithelium. This release allows free exchange between CSF and nervous tissue of brain and spinal cord, which is why sampling of CSF (e.g. through a "spinal tap") provides a window to the CNS.
The basal membranes of these cells are characterized by tentacle-like extensions that attach to astrocytes.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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