Cell theory is a scientific theory that explains how living organisms are built. It was first formulated in the mid-19th century by two scientists named Matthias Schleiden and Theodor Schwann. The theory emphasizes that all living beings are made up of a basic life unit called a "cell," and each of the bodys cells has started its life journey from a pre-existing cell only. The generally accepted parts of modern cell theory include:
- All known living things are made up of one or more cells.
- All living cells arise from pre-existing cells by division.
- The cell is the fundamental unit of structure and function in all living organisms/04%3A_Cell_Structure/4.03%3A_Studying_Cells_-_Cell_Theory).
The history of cell theory is a history of the actual observation of cells, because early prediction and speculation about the nature of the cell were generally unsuccessful. The decisive event that allowed the observation of cells was the invention of the microscope in the 16th century, after which interest in the "invisible" world was stimulated. By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory/04%3A_Cell_Structure/4.03%3A_Studying_Cells_-_Cell_Theory). Rudolf Virchow later made important contributions to this theory, adding that all cells have arisen from some pre-existing cells.
