The classical bilayer model of cell membrane structure proposed by Singer and Nicholson in 1972 has recently been modified. Research has shown that lipid molecules in the membrane do not have a random horizontal distribution but form submicroscopic domain enriched in cholesterol, sphin- golipids and gangliosides. These lipid microdomain (also named lipid rafts) have been visualised in living cells by a variety of methods including fluorescence microscopy with lipid-specific probes, scanning probe microscopy and cryoelectron microscopy.