Differences in Ultracytochemical Localization of Na-K Dependent Atpase in the Rat Choroid Plexus and Ependyma

The ventricular ependyma shares a common embryological origin with the choroid plexus (1). These epithelia have many structural and ultrastructural similarities, and both have been considered probable sites of cerebrospinal fluid (CSF) secretion (2,3). The purpose of the present study is to investigate the localization of Na-K dependent (transport) ATPase in rat ventricular ependyma and to compare these findings with the results of previous studies on the choroid plexus. Adult male Wistar rats were perfused through the heart with 3% depolymerized paraformaldehyde in 0.1M cacodylate buffer (pH 7.3). The brain was rapidly removed and samples of cerebral ependyma with adjacent white matter and choroid plexus were excised and placed in a vial where prefixation continued for 30 minutes at room temperature.