Neurons and Interneuronal Connections: a Historical Overview -- Some Evolutionary Aspects and General Features of Neurons -- Shape and Size of Neurons -- Different Types of Neuron -- The Structure of Neurons -- The Perikaryon -- The Nucleus -- Dendrites -- Age-Related Changes -- The Axon -- The Plasma Membrane -- Intercellular Junctions Involving Neurons -- Interneuronal Adherent Junctions -- Interneuronal Chemical Synapses -- Autapses -- The Neuromuscular Junction -- Structural Aspects of Synaptic Activity -- Synaptic Structural Plasticity -- Age-Related Changes -- Relationship Between Axons of the Autonomic Nervous System and Effector Cells -- Electrotonic and Mixed Junctions -- Synapse-Like Junctions Involving Neuroglial Cells -- Other Types of Interneuronal Communication -- The Neuroglia of the PNS -- The Satellite Cells of Sensory and Autonomic Ganglia -- Schwann Cells and the Myelin Sheath -- Other Neuroglial Cells of the PNS -- Functions of the PNS Neuroglia -- Neuron-Glia Communication -- The Neuroglia of the CNS -- Historical Note -- Some Evolutionary Aspects -- The Ependyma -- The Choroid Epithelium -- Astrocytes -- Oligodendrocytes -- NG2-Expressing Cells -- Renewal of the Neuroglial Cell Population -- Microglial Cells -- Historical Note -- Resting Microglia -- Neural Macrophages -- Age-Related Changes -- The Cellular Organization of the CNS -- The Blood Vessels of the CNS -- Arteries -- Capillaries and the Blood-Brain Barrier -- Veins -- Cells Associated with Microvessels -- Age-Related Changes.