The Fine Structure of Ependymal Cells

Part 1. The Fine Structure of Ependymal Cells in the Kitten

Abstract

Thirty kittens, 15 to 30 days old, were used in the present study. They were infused and then fixed with glutaraldehyde, followed by the post-fixation with osmium tetraoxide. Afterwards, the ependymal cells and the nerve fibers distributed in the ependyma were studied with electron microscope.
The fine structures of kitten ependymal cells were similar to those of other animals so far rerorted, but there were some characteristic findings of this experimental animal. Those were as follows: 1) the deep nuclear indentations above which a large number of cell organelles were situated in the apical cytoplasm; 2) the presence of filamentous structures, namely, filaments about 70 to 80Å and microtubules about 150 to 200Å in diameter; 3) the presence of a few number of vesicular components; 4) the presence of abundant ependymal tanycytes, whose processes were frequently in direct contact with the subependymal blood vessels.
The present study also revealed that there were nerve fibers at the free surface of the ependyma in several regions of the ventricular system. The nerve fibers contained microtubules about 200Å in diameter, vesicles of varying sizes and dense mitochondria with longitudinal cristae. They terminated in two different types of endings after projecting into the ventricle: the first was a stout club-like projections in which there were centrally accumulated mitochondria, and the second was a slender expansions which were frequently clustered and formed into plexus.