a basic tenet of modern biology, first stated by Matthias Schleiden and Theodor Schwann in 1838–39, that cells are the basic units of structure and function in living organisms.
Main Entry: cell theory Function: noun : a theory in biology that includes one or both of the statements that the cell is the fundamental structural and functional unitof living matter and that the organism is composed of autonomous cells with its properties being the sum of those of its cells
