In the cerebellar cortex ofMacaca cynomolgus there are all types of glial cells as well as in other species. In the astrocytes, the Fañanas-cells and the microglia very often enlarged cisterns of the ergastoplasm occur in which tubular structures are located. These structures consist of very closely packed tubules with a diameter of 200 Å. The wall of the tubules is formed by a very fine granular material, their lumen is empty. These tubular structures of glial cells are only found in the cerebellar cortex. A possible similarity to viruses is discussed.
