Ultrastructural Changes in the Ependyma of the Septum Pellucidum in Acute Experimental Hydrocephalus in the Rhesus Monkey

Intercellular spaces separate ependymal cells from one another except where they are united by cellular junctions. Two types of gap junctions exist between these cells. It had been previously thought that one of these was a true tight junction, but recently it has been shown to be a seven layered gap junction. The stability of epithelial junctions under stress in tissues other than brain is well documented. Light microscopic studies currently in progress have indicated that the ependyma of the septum pellucidum becomes severely stretched within a matter of hours following experimental obstruction of the 4th ventricle by a technique described by Milhorat. It was therefore decided to investigate this area with the electron microscope in order to study the junctions under such severe stress.