ELECTRON MICROSCOPY OF CLASSICALLY STAINED ASTROCYTES

Sections of cat cerebral cortex stained for astrocytes by the Cajal gold chloride-sublimate method have been examined with the electron microscope. Small, electron-opaque dots representing gold deposition are specifically concentrated in cells which have swollen, clear perikaryal areas and processes which terminate as perivascular end feet. The appearance of these cells is very similar to the "watery" cells identified as astrocytes in some of the early electron microscopic investigations of central nervous tissue. Neurons and oligodendrocytes, in those layers of cortex examined electron microscopically, contain only a small number of gold particles. A possible morphological substrate explaining the specificity of the Cajal method for astrocytes is discussed.