Ultrastructure of the central nervous system: the basics.

Since the articles in this supplement describe ultrastructural changes in diseases of the nervous system, for better understanding of these papers dealing with pathology of the this system, basic elements of the ultrastructure of the central nervous system are presented in this survey. Description of the fine structure of cells and fibres of the central nervous system presented below is based on classical textbooks as well as on the authors' personal experience. The details of ultrastructure of nerve cells (their nucleus and cytoplasm, including cell organelles: abundant granular endoplasmic reticulum, prominent Golgi apparatus, mitochondria, lysosomes, as well as other cell components including: neurofilaments, lipid droplets, multivesicular bodies, lipid droplets, lipofuscin granules, and in some cells melanin granules, and also cell processes), the interneuronal chemical synapses (specialized site of interneuronal communication) as well as all types of neuroglial cells (a class of non-neuronal supporting cells): astrocytes (fibrous and protoplasmic), oligodendrocytes, and microglia neuroglial cells are described.