Scanning electron microscopy of the wall of the third ventricle of the brain of Rana temporaria. III. Electron microscopy of the ventricular surface of the median eminence.

From combined scanning and transmission electron microscopic studies it is concluded (1) that all surface specializations of the median eminence of Rana temporaria are protrusions of ependymal cells; (2) that the microvillus-like structures of the median eminence are transient differentiations of the ependymal cell surface, associated with the activity of the ependymal cells.