Definitions for "Cell theory"
The doctrine that every living organism is composed of cells and that all cells come only from other preexisting cells.
(1) All organisms are composed of one or more cells; (2) cells themselves are alive and are the basic living unit of function and organization of all organisms; (3) all cells come from other cells.
(biology) the theory that cells form the fundamental structural and functional units of all living organisms; proposed in 1838 by Matthias Schleiden and by Theodor Schwann