This atlas of functional ultrastructure provides a detailed insight into the complex structure and organization of cells and tissues. Further, highlights of specific cellular and tissue functions, as well as the dynamics of diverse intracellular processes are provided. Highly informative and high-quality electron micrographs are complemented by explanatory texts, selected references and schemes. Emphasis is placed on an integrated view of structure and function to illustrate the concept that subcellular organelles provide the structural foundation for fundamental processes of living organisms. The first part of the atlas covers the cellular organelles, and illustrates their characteristic changes due to experimental manipulations or occurring under pathological conditions. The second part then illustrates the principles of tissue organization and function, including selected examples ranging from diverse epithelia and mesenchymal cells to muscle and sensory cells, cells of the nervous system and of the peripheral blood. In addition to their normal appearance, typical fine structural changes resulting from experimental induction or pathological situations complete this part of the atlas.