Animal Cells - History of Research

History of Research

• 1632–1723: Antonie van Leeuwenhoek teaches himself to make lenses, constructs simple microscopes and draws protozoa, such as Vorticella from rain water, and bacteria from his own mouth.
• 1665: Robert Hooke discovers cells in cork, then in living plant tissue using an early compound microscope.
• 1839: Theodor Schwann and Matthias Jakob Schleiden elucidate the principle that plants and animals are made of cells, concluding that cells are a common unit of structure and development, and thus founding the cell theory.
• 1855: Rudolf Virchow states that cells always emerge from cell divisions (omnis cellula ex cellula).
• 1859: The belief that life forms can occur spontaneously (generatio spontanea) is contradicted by Louis Pasteur (1822–1895) (although Francesco Redi had performed an experiment in 1668 that suggested the same conclusion).
• 1931: Ernst Ruska builds first transmission electron microscope (TEM) at the University of Berlin. By 1935, he has built an EM with twice the resolution of a light microscope, revealing previously unresolvable organelles.
• 1953: Watson and Crick made their first announcement on the double-helix structure for DNA on February 28.
• 1981: Lynn Margulis published Symbiosis in Cell Evolution detailing the endosymbiotic theory.