ependymal

Ependymal refers to the ependymal cells that line the ventricles of the brain and the central canal of the spinal cord. They form the ependyma, a single-layer, neuroepithelial lining that covers the ventricular surfaces.

Ependymal cells are generally simple cuboidal to columnar in shape. Their apical surfaces bear cilia and microvilli, which help circulate cerebrospinal fluid. They are joined by tight and gap junctions, creating a selective barrier between the CSF and brain tissue in most areas. In the choroid plexus, a specialized group of ependymal‑like cells have a highly developed secretory capacity and contribute to the formation of cerebrospinal fluid as part of the blood-CSF barrier.

The ependymal lining helps regulate CSF composition and flow. Motile cilia generate directional movement of CSF through the ventricular system. In addition to CSF production in the choroid plexus, ependymal cells contact neural progenitor cells in certain regions and may participate in aspects of adult neurogenesis.

Ependymal cells originate from the neural tube neuroepithelium during embryogenesis. A specialized subtype, tanycytes, lines the floor of the third ventricle and has processes extending into hypothalamic regions, illustrating regional specialization of the ependymal lineage.

Clinical relevance includes tumors arising from ependymal cells, known as ependymomas, typically located in the ventricles or spinal cord. Disruption of ependymal function or obstruction of CSF pathways can contribute to hydrocephalus, emphasizing the role of the ependymal lining in CNS homeostasis.