SUPRAEPENDYMAL NEURONAL ELEMENTS OF THE FLOOR OF THE 4TH VENTRICLE INADULT-RAT - A SCANNING ELECTRON-MICROSCOPIC STUDY

Scanning electron microscopic studies of the floor of the fourth ventr icle revealed the presence of a cluster of neuron-like structures and an extensive network of fibers on the ependymal surface. These supraep endymal cell clusters are found on the sparsely ciliated regions of th e fourth ventricle. The surface of these cells is richly covered with nerve ending-like structures of varying size and shape. Long cables of intertwined fibers are present all over the surface of the fourth ven tricular floor. Majority of these fibers are varicose in nature. Some of these fibers end blindly as round or ellipsoid thickening in the ve ntricular cavity. The widespread occurrence of supraependymal structur es of the third and fourth ventricles, which are presumed to be neuron s, nerve fibers and free floating nerve endings in the cerebrospinal f luid (CSF), suggest that they potentially function as an additional pa thway of intraventricular communication.