AbstractThis study of the fine structure of the neuroglia in the spinal cord of the newt,Triturus viridescens, has permitted the identification of three types of glial elements. One type is the ependymal cell whose processes are rich in filaments and glycogen and end on the pia in the deeper portion of the fissures of the cord. The two other types of glial cells display some morphological similarities to typical mammalian neuroglia although they appear to be more primitive. These are the astrocytes and oligodendrocytes. The astrocytes contain glial filaments, glycogen, specialized mitochondria, few ribosomes, and probably send end feet to the surface of the cord and to the intramedullary vessels. The oligodendrocytes present some variation in morphology but always exhibit an abundance of ribosomes. They are located either near the neurons, the intramedullary vessels, the pia, or the myelin sheath.