Abstract
This paper describes the fine structure and the morphological polarization in the ependymal cilia and their basal feet on the ventral stalk of the rat subfornical organ. The cilium contains nine outer fibers arranged in a regular circle in the usual pattern about a central pair of fibers. One particular pair of outer fibers (numbers 5 and 6) is often joined together by a bridge, such as has been described previously in the cases of the sperm tail (Afzelius ’59) and of the mussel cilia (Gibbons ’61). Within the transitional region of the cilium, the central fibers terminate and the basal plate is present. The triplicate basal body projects usually one basal foot at a location corresponding to its outer fibers 5 and 6, but sometimes it project s multiple basal feet in all directions. The basal foot consists of three fundamental component: the “foot filaments” which extend from the outer fibers 5 and 6 or the surrounding granules, and the electron density is increased at one part of the whole course of about 200 mµ; the “foot plate”, a disc about 200 mµ in diameter and about 25 mµ thick, is composed of a compact accumulation of granular materials, on which the foot filaments terminate; and the “granular coat” which is also a granular material accumulated loosely on the foot plate similar to the sugar coating in a medicinal tablet. The basal foot forms the polarization on the ciliary structure. The directions of polarization of the ependymal cilia approximately, but not strictly, coincide in the area of the ventral stalk of the subfornical organ as well as in a part of the single cell surface. The ciliary polarizations often deviate slightly even between the cilia lying side by side, sometimes largely and occasionally in the opposite directions. All the ependymal cilia do not always extend in the same direction, with an even distribution and from the same plane, in the apical cell cytoplasm. The relationship between the polarization of the ependymal cilia and the flow of the cerebrospinal fluid is discussed.
