The subependymal plate of the hypothalamus of the hamster has been studied in this work. Our observations with the electron microscope show that the basal surface of the ependymal cells in this area are situated directly over the astrocytic elements. Ultrastructural studies which indicate two types of glial cells in the subependymal plate contradicted by the results of the present investigation demonstrating one type of glial cells in the hypothalamic subependymal plate. This fact is interpreted as the final result of a glial differentiation in adult hamsters.