In recent decades, genetic, biochemical, immunological, and cell biological techniques have been applied not only for better understanding of pathogenesis of known mitochondrial encephalomyopathies but also for exploring the possibility of mitochondrial involvement in other neurological, cardiac, gastrointestinal, and urological diseases. Techniques applied in a coordinated fashion have made it clear that mitochondrial dysfunction plays an important role in a wide range of human diseases including degenerative, toxic, metabolic, and neoplastic disorders. In this chapter, we provide updated protocols of essential histochemical and immunohistochemical methods that, in our opinion, are the most reliable morphological tool to visualize respiratory chain abnormality on tissue sections.
