Cell Theory

As microscopes improved throughout history, scientists were able to better examine what living tissues were made of. They often found that living organisms were composed of small compartments or pores. Robert Hooke was the first scientist to name these "cells" in 1665, after the small rooms that monks inhabit.

Two scientists are credited with developing cell theory. Matthias Jakob Schleiden was a botanist who found cells in all plants he examined. In 1839, Theodor Schwann, a physiologist found that he also found cells in animal tissues. Together, they postulated the first two of the three cell theory tenets. However, where cells came from was still debated until, in 1855, Rudolf Virchow, a pathologist, added the third tenet to cell theory.

The three tenets of cell theory are:

1. All living organisms are composed of cells
2. Cells are the structural and organizational unit of life
3. All cells come from pre-existing cells