Histology: the study of the microscopic anatomy (microanatomy) of cells and tissues of plants and animals. It is commonly performed by examining cells and tissues under a light microscope or electron microscope, the specimen having been sectioned (cut into a thin cross section with a microtome), stained, and mounted on a microscope slide. The ability to visualize or differentially identify microscopic structures is frequently enhanced through the use of histological stains.