Cytoplasm is the material that makes up the body of a cell. It is made up of water, proteins, and organelles such as mitochondria, lysosomes, and the nucleus. The cytoplasm is surrounded by a thin barrier called the cell membrane that separates the inside of the cell from the external environment. Cytoplasmic is another term pathologists use when describing the cytoplasm of a cell.
Pathologists use a combination of stains called hematoxylin and eosin (H&E) to see cells under the microscope. When viewed under the microscope, eosin makes the cytoplasm of the cell appear pink. The amount of cytoplasm inside a cell varies between different types of cells. For example, squamous cells on the surface of the skin have a large amount of cytoplasm. In contrast, specialized immune cells called lymphocytes have very little cytoplasm.
Pathologists use a variety of special terms to describe the look of a cell’s cytoplasm under the microscope. For example, the terms eosinophilic and oncocytic describe cells that have a large amount of bright pink cytoplasm. The term clear is used to describe cells that look transparent or white because they contain very little eosin. Basophilic is used to describe cells that appear more blue than pink as a result of the stain hematoxylin sticking to material in the cytoplasm.