Walsh & Hoyt: Ependymal Tumors

The ventricles, the central aqueduct of Sylvius, and the central canal of the spinal cord are covered by a single layer of cuboidal ependymal cells that normally lie side by side in palisade formation. Their nuclei are oval and somewhat longer and more darkly staining than the nuclei of astrocytes and are normally arranged in a regular line. The outer portion of the cell consists of one or more tapering processes that contain fine fibrils that pass into and merge with the underlying nervous tissue. The inner (ventricular) part of the cell body is cylindrical and ciliated. At the base of the cilia are PTAH-positive structures called basal bodies or blepharoplasts, which provide absolute evidence that the cell is ependymal in origin.