The science concerned with the chemistry of cells. Specifically, the macromolecules of subcellular structures can be treated chemically to form microsopically visible end products. For example, proteins, enzymes, lipids, carbohydrates, and nucleic acids can be directly visualized in cell nuclei, membranes, and organelles by cytochemical methods which generate images that can be viewed by either bright field or light, fluorescence, confocal, or electron microscopes.