Morphology of the ependymal cells of the bovine area postrema.

This communication describes the ultrastructure of the ependyma of the bovine area postrema. The polygonal cells possessed an abundant apical array of microvilli but were nonciliated with the exception of occasional cells at the periphery of the area, which had a central kinocilium. The low squamous cells contained moderate numbers of cytoplasmic organelles. The cells do not appear to be typically secretory, but may function in fluid exchange.