: a small cavity or space in the tissues of an organism containing air or fluid
: a cavity or vesicle in the cytoplasm of a cell containing fluid
Illustration of VACUOLE
Space within a cell that is empty of cytoplasm, lined with a membrane, and filled with fluid. Especially in protozoans, vacuoles perform functions such as storage, ingestion, digestion, excretion, and expulsion of excess water. The large central vacuoles often found in plant cells enable them to attain a large size without accumulating the bulk that would make metabolism difficult.