Cytochemistry is the branch of science that focuses on the chemical composition and processes within cells. It combines techniques from both cytology, the study of cell structure, and biochemistry, the study of chemical processes in living organisms. By using various staining methods and chemical assays, researchers can visualize and analyze specific cellular components, such as proteins, nucleic acids, and lipids. This field is essential for understanding cellular functions and identifying abnormalities in diseases. For instance, immunocytochemistry is a technique used to detect specific proteins in cells, aiding in cancer diagnosis and research. Overall, cytochemistry plays a crucial role in advancing our knowledge of cellular biology.