1 Introduction.- 2 General Characteristics of the Satellite Cell Sheath in the Adult Animal.- 3 Shape of Satellite Cells.- 4 Structure of Satellite Cells.- 4.1 Plasma Membrane.- 4.2 Nucleus.- 4.3 Cytoplasmic Organelles.- 4.4 Cytoplasmic Lacunae.- 4.5 Cell Inclusions.- 5 Relationships Between Satellite Cells.- 6 Perikaryal Myelin Sheaths.- 7 Neuron-Satellite Cell Boundary.- 8 Boundary Between the Satellite Cell Sheath and the Connective Tissue Space.- 9 Quantitative Relationships Between Nerve and Satellite Cells in the Adult.- 10 Origin and Development of Satellite Cells.- 10.1 Origin.- 10.2 Development.- 10.3 Neuron-Satellite Cell Boundary.- 10.4 Boundary Between the Satellite Cell Sheath and the Connective Tissue Space.- 10.5 Quantitative Relationships Between Nerve and Satellite Cells.- 11 Chemical and Cytochemical Aspects of Satellite Cells.- 12 Mitotic Activity of Satellite Cells in Adult Animals.- 13 Phagocytic Activity of Satellite Cells.- 14 Functional Properties of Satellite Cells.- 15 Satellite Cells in Tissue Cultures.- 16 Reaction of Satellite Cells to Experimental Conditions.- 16.1 Chemical Agents.- 16.2 Radiation.- 16.3 Axonal Injury.- 16.4 Other Experimental Conditions.- 16.5 Conclusions.- 17 Reaction of Satellite Cells to Pathologic Conditions.- 17.1 Viral Infections.- 17.2 Hereditary Neuropathies.- 17.3 Other Pathologic Conditions.- 17.4 Reaction of Satellite Cells to Neuronal Degeneration.- 18 Roles of Satellite Cells in Sensory Ganglia.- 18.1 Mechanical Support for Ganglionic Neurons.- 18.2 Control of the Traffic of Materials to and from the Ganglionic Neuron.- 18.3 Control of the Levels of Neuroactive Amino Acids.- 18.4 Trophic Role Toward the Ganglionic Neurons.- 18.5 Regulation of Ion Concentration in the Micro-environment of Ganglionic Neurons.- 18.6 Influence of the Conduction Velocity in Bipolar Sensory Neurons.- 18.7 Production of the Basal Lamina and Collagen Fibrils.- 19 Comparison of Satellite Cells of Sensory Ganglia and Neuroglial Celcb