Lysosomes are located in the cytoplasm of a eukaryotic cell and are composed of membrane enclosed bags of hydrolytic enzymes. They are common in animal cells, but rare in plant cells. Lysosomes contain the hydrolytic enzymes necessary for intracellular digestion. They are digestive organelles where macromolecules are hydrolysized. In an electron microscope, lysosomes appear as dark spots with an outline for a membrane.