Ependyma


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ependyma

[e′pen·də·mə]
(histology)
The layer of epithelial cells lining the cavities of the brain and spinal cord. Also known as ependymal layer.

Ependyma

 

cells in the brain of animals and man that perform demarcating, supportive, and secretory functions in the central nervous system; a form of neuroglia.

The ependyma separates from cells of the neural tube in early embryogenesis. Ependymal cells (ependymocytes) line the walls of the spinal canal and ventricles of the brain. They have elongated bodies with cilia at the free end. The cilia, which are lost in many parts of the brain after the individual is born, help the cerebrospinal fluid to circulate by their beating movements. A long, branched process extends from the opposite end of the ependymocyte into the brain. The ependyma of the walls of the third ventricle may promote the exchange of biologically active substances between neurons of the adjacent regions of the brain, cerebrospinal fluid, and blood vessels of the hypophyseoportal system.

References in periodicals archive ?
The structure of the cerebral ventricles is subjected to significant changes which enclose marked polymorphism of ependyma cells, disturbances of their continuity of their layer at considerable length.
Unfortunately, the ependyma may be destroyed by significant dilatation of the central canal.
A few studies, however, indicated for an alternative pathway of virus entry following direct intbction of microvascular endothelial cells of the blood brain barrier (31), Following entry the second step is getting past the glia limitans (layer formed due to astrocytic end foot interdigitating with piamater along the surface and ependyma along the ventricles) which is an additional barrier both functionally and structurally.
Medially the MD is lined with 3rd ventricular ependyma lying immediately adjacent to the 3rd ventricle, except where the paraventricular nucleus is interposed.
Ependymomas originate from the ependyma cells, which are lining the spinal cord's central canal.
Posthemorrhagic hydrocephalus is defined as progressive ventricular dilatation after an IVH, either acute (caused by either a blood clot that impairs the normal flow of cerebral spinal fluid [CSF], or obstruction to the absorption of CSF at the level of the arachnoid villi), or chronic (due to obliterative arachnoiditis or blockage from necrotic debris, reactive gliosis, or disrupted ependyma that interferes with flow of the CSF).
They were located near the soft cerebral membrane, chiefly in the regions of the posterior long fasciculi, the nuclei of the abducent vestibular and trigeminus nerves, under the ependyma, in the area of the cochlear nerve nuclei, the Gover's fasciculi, and in the base of the cerebellum.
In this case, the ependyma is reconstituted by the transformation of the ependymal cells into nonepithelial mesenchymal cells, which proliferate from both edges of the lesion to bridge the gap, then transform back into epithelial cells, while axons regenerate to make functional synapses.