Fine structure of the ependymal cells in the area postrema of the domestic fowl.

The ultrastructure of the ependymal cells in the area postrema of the domestic fowl was studied by scanning and transmission electron microscopy. The ependymal surface of the area postrema is covered with many furrows and ridges. These ridges consist of ependymal cells aggregated in a fan-like shape. The ependymal cell lacks clustered cilia, microvilli are few, and a long basal process extends through the parenchymal layer of the area postrema. Within the cytoplasm as well as in the basal process, a spherical body with a diameter ranging from 1.5 to 2 micron is occasionally observed.