1. HANS AND ZACHARIAS JANSSEN
In 1590, these two gentlemen produced the first compound microscope by combining two convex lenses within a tube.
ANTON VAN LEEUWENHOEK
He improved magnification of microscopes by polishing lenses. Moreover in the 1680’s, he observed living cells through a microscope. He also discovered bacteria from a sample of saliva from his mouth

2. In 1838, he discovered that plants were made up of cells
ROBERT HOOKE
In 1665 an English scientist, Robert Hooke, discovered cells in a piece of cork, which he examined under his primitive microscope. Actually, Hooke only observed cell walls because cork cells are dead and without cytoplasmic contents. Hooke drew the cells he saw and also coined the word CELL. 
MATTHIAS SCHLEIDEN
In 1838, he discovered that plants were made up of cells

3. THEODOR SCHWANN
In 1839, he discovered that animals were made up of cells
RUDOLPH VIRCHOW
In 1855, he stated that all living cells come from other living cells/things

4. Adapted from utahscience

5. From utahscience