Ultrastructural Aspects of Ependymal Cells Covering the Feline Area Postrema

Recent ultrastructural examination of the feline area postrema (AP) demonstrated that the ependyma that covers this circumventricular organ shows several morphological characteristics that distinguish it from typical mural ependyma. Cat AP ependyma lacks the cilia present on the surface of typical mural ependyma but has numerous microvillar projections. The apical portions of AP ependyma are connected by zonula adherentes while maculae occludentes,which characterize mural ependyma,are not obvious. Subcellular organelles present in AP ependyma include: mitochondria, inclusion bodies, Golgi and endoplasmic reticulum of both rough and smooth varieties. While all of these organelles are normally present in mural ependyma, cat AP ependyma sometimes displays a whorled type array of endoplasmic reticulum.</jats:p