Cell Theory

By 2700

  • First Compound Microscope

    Two spectacle-makers, Hans and Zacharias Janssen, constructed the first compound microscope using two lenses inside a tube.

  • Robert Hooke further developed the compund microscope

    He described cells as ‘… all perforated and porous, much like a honeycomb… the pores or cells… consisted of a great many little boxes…’

  • Anton van Leeuwenhoek observed unicellular organisms

    described unicellular organisms from his observations of a drop of stagnant rainwater as ‘animalcules’. Leeuwenhoek also soaked some peppercorns in water for several days. When he examined a drop of this water under his microscope, he did not fi nd the little needles he expected that made pepper ‘hot’, just more unicellular organisms. 1683 Leeuwenhoek discovered bacteria

  • Leeuwenhoek discovered bacteria from his observations of saliva

  • René Dutrochet stated that all animals and plants are made up of cells

  • Robet Brown discovered the necleus

  • Matthias Schleiden and Theodor Schwann formulated the cell theory

    The cell thoery is that all living matter is composed of small units called cells.

  • Rudolf Virchow stated that ‘where a cell exists there must have been a pre-existing cell, just as theanimal arises only from an animal and the plant only from a plant.’

  • Carl Zeiss and Ernst Abbe produced the fi rst oil immersion objectives. Images could be magnifi ed over 1000×.

  • Walther Flemming described cell division (mitosis) from observations on living and stained cells.

  • Ernst Ruska built the fi rst electron microscope.

    Transmission electron microscopes and scanning electron microscopes were developed in the following decades. Details of internal cell structures were revealed.

  • Paul Kirkpatrick and Albert Baez built the fi rst X-ray microscope that used soft X-rays.

    Soft X-rays produce diffraction images that allow non-crystalline specimens, from single protein molecules to cells, to be viewed.

  • Marvin Minsky developed the fi rst confocal microscope.

    These laser-based scanning microscopes can produce threedimensional images of cells and cell structures.

  • Two-photon fl uorescence microscope developed by Winfried Denk.

    This massive microscope uses laser light that creates three-dimensional images within tissues, without damaging cells