The relations of ependyma to neurons and capillaries in the hypothalamus: A Golgi‐Cox study

Abstract Numerous basal processes of ependymal cells extend peripherally into every cell group and area of the hypothalamus of the four species of mammals examined: mouse, rat, rabbit and cat. With Golgi‐Cox impregnation and Nissl counterstaining, ependymal cell processes appear to have a variety of forms and of intricate structural relationships with neurons and capillaries within the hypothalamus. It is proposed that hypothalamic ependymal cells and their processes function as a communication system between the cerebrospinal fluid of the third ventricle and neurons and capillaries within the hypothalamus. The role that such a system may play in the regulation of adenohypophysial function is discussed. It was also noted that in all hypothalamic cell groups, dendrites of some neurons extend to the ependymal layer. An unusual cell, resembling microglia forms, within the infundibular nucleus appears to be selectively impregnated by the Golgi‐Cox technique employed. The cell is characteristic of the infundibular nucleus and, with rare exceptions, is confined to that cell group. Some of these spider‐cells lie on the ependymal layer and also have endfeet extending to the ventricular surface of the ependyma.