Historical Developments that led to Current Fluid Mosaic Model
1917 - Irving Langmuir made artificial membranes experimentally by creating a monolayer of lipids
          on the surface of water
Langmuir Trough*. The polar heads interacted with water, and nonpolar tails
          projected into the air.
1925 - Evert Gorter and F. Grendel proposed that lipids form bilayers around cells*. This was based on
           measurements of lipid content enclosing red blood cells. They extracted RBC lipids and showed
           there was enough lipid (based on surface area) to surround the cell with two layers.
1935 - Hugh Davson and James Danielle propose model of cell membrane in which  the phospholipid bilayer
           lays between two layers of globular proteins - figure*.
1950s - Electron microscopy studies carried out by J.D. Robertson and others revealed that membranes
            look like a train track—two dark lines separated by a light space*.  Researchers determined that
            the dark lines in these experiments are the phospholipid heads, which were heavily stained,
            whereas the light region between them is their phospholipid tails.
1966 - Using freeze fracture electron microscopy (figure*), Daniel Branton concluded that membranes
           are bilayers, because the freeze fracture procedure splits membranes in half, thus revealing
           proteins in the two membrane leaflets.
1972 - S. Jonathan Singer and Garth Nicolson proposed a fluid-mosaic model*.
           Their model was consistent with the observation that membrane proteins are globular, and some
            are known to span the phospholipid bilayer and project from both sides.
            Fluid Mosaic interpretation*   and   extra cellular matrix*.
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