The ependymal layer is a thin membrane that lines the ventricles of the brain and the central canal of the spinal cord. The word "ependymal" is pronounced [ɪˈpɛndɪməl], with the stress on the second syllable. The "e" in the first syllable is pronounced as the short "i" sound, while the "y" in the second syllable is pronounced as a long "i". The final "al" is pronounced with a schwa, represented by the upside-down "e" symbol, making the sound [əl].
The ependymal layer is a specialized layer of cells that lines the ventricles and central canal of the brain and spinal cord. It consists of ependymal cells, which are a type of glial cell responsible for several important functions within the nervous system.
The main role of the ependymal layer is to produce, maintain, and circulate cerebrospinal fluid (CSF) that surrounds and protects the brain and spinal cord. Ependymal cells possess cilia on their surface that help in the movement of CSF, aiding its circulation throughout the ventricles and central canal. This movement is crucial for the delivery of nutrients, removal of waste products, and regulation of the brain's microenvironment.
Additionally, the ependymal layer acts as a barrier between the CSF and the brain tissue, controlling the transport of substances between these compartments. It has selective permeability, allowing for the exchange of ions, nutrients, and certain molecules while preventing the passage of potentially harmful substances.
Beyond its structural and protective functions, the ependymal layer also participates in certain processes related to neural development and repair. It can contribute to the formation of new neurons and glial cells, as well as promote the migration of neural stem cells.
In summary, the ependymal layer is a vital component of the central nervous system, responsible for the production and circulation of cerebrospinal fluid, maintaining brain homeostasis, and participating in neurodevelopmental and repair processes.
Ependyma layer.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "ependymal" is derived from the Greek terms "epi" meaning "upon" or "on" and "endyma" meaning "garment" or "covering". In the context of biology, it refers to a layer or covering that lies upon or covers something. The term "ependyma" specifically refers to a type of tissue that lines the ventricles of the brain and the central canal of the spinal cord. Therefore, the term "ependymal layer" denotes the layer of ependymal tissue.