Ependymal cells are part of the lining of the brain and ventricles. They are normal neural lining cells that are sometimes seen in cerebrospinal fluid (CSF) smears from children but rarely seen in smears from adult CSF samples. They produce CSF and are involved in circulating the CSF over the brain, ventricles, and the spinal cord.
These cells may be present in cases of hydrocephalus or chronic ventricular infection. They usually appear as very large multinucleated clumps. The ependymal clump in the image on the right allows you to get a perspective of the potential size compared to the surrounding RBCs.