Molecular architecture of the presynaptic compartment studied by cryo-electron tomography

Cryo-electron tomography allows the three dimensional visualization of cells and other biological material in a frozen, close-to-life state. In order to achieve the best preservation of the biological structures, the samples must be frozen in a manner that only vitreous ice is formed. High-pressure freezing is the method of choice for vitrification of tissue samples, whereas dissociated cells can simply undergo plunge freezing. Once frozen, the samples are inserted directly into the electron microscope, therefore avoiding dehydration and use of chemical fixatives, necessary for conventional electron microscopy (EM).