Ependymal cells surface of human third brain ventricle by scanning electron microscopy.

The ependymal lining of the human brain ventricular system displays distinct structural differences and functional heterogeneity among individual ependymal cells (ECs). To date, multi-ciliated ECs (E1 cells), bi-ciliated ECs (E2 cells), uni-ciliated ECs (E3 cells), ECs without cilia, and ECs with cytoplasmic protrusions have been described in human brain ventricles. Using scanning electron microscopy (SEM), we evaluated ependymal samples from 6 defined regions of the third ventricle from 9 human brains. These regions were strictly defined according to the periventricular structures they neighbour with. We observed different structures on the apical surface of the ECs. Various ECs differed from each other by the presence of microvilli, secretory bodies, and a variable number of cilia, which led us to divide the ECs into several exactly specified types according to their apical morphology. We found all types of ECs in every examined region with a predominance of particular types of apical surface of ECs in the individual areas (Tab. 4, Fig. 7, Ref. 22).