Some new cytological observations of the normal rat ependymal cell

The ependyma of the lateral ventricle of normal adult rats fixed by intravascular perfusion with either glutaraldehyde or formaldehyde was examined with the electron microscope. Three main observations of the normal ependymal cells were made which, to our knowledge, have not yet been reported. Ependymal cells were occasionally found directly abutting on blood vessels in the immediate vicinity. In this respect, they were very much like the well‐known perivascular astrocytes and tanycytes. This similarity was strengthened by the morphological details of the junctional areas. Bundles of the fine fibrils (app. 60 Å) were seen in the nuclei. They were devoid of any membranous boundary and were apparently identical to the fibrils often seen in the perinuclear cytoplasm. Microtubules, occasionally containing approximately 50 Å central densities, were consistently seen in the apical cytoplasm. They were apparently identical to the familiar microtubules constituting the cillary fine structure which also contained occasional central densities.