An illustration of the Tokuyasu method.
Figure by Neta Varsano

In the Tokuyasu procedure, the sample is fixed using a moderate fixative, typically 0.1% GA 4% PFS in Cacodylate buffer, after which the cell pellet is embedded in gelatin, cut into small cubes, and immersed in sucrose for 48-72 hours.
The sample is then placed on a stub and frozen in liquid nitrogen. The material is subsequently cryosectioned into 80-100 nm slices, using a cryo ultra-microtome. The sections are placed on a TEM grid and allowed to thow. The sections can then be labeled with antibodies that specifically target molecules of interest, while coupled to gold particles or fluorescent markers. Tokuyasu sections are ideal substrates for immuno-labeling, since antigens are not exposed to organic solvent dehydration or obscured by resin. Instead, the structures remain fully hydrated throughout the labeling procedure. Furthermore, antibodies can access target molecules within dense intercellular structural elements, cells, and organelles through the section surface. Following antibody labeling and light microscopy imaging, the sections are stained with UA, embedded in methylcellulose, and observed using a transmission electron microscope.
The light microscope image and the TEM image can then be superimposed to show fluorescence labeling in specific compartments of the sample.
It is typical for Tokuyasu sections to have areas with negative membrane contrast, in which the membranes appear bright against dark background as opposed to conventional preps where membrane contrast is positive.  It is also common for the section to display some compression artifacts, However, this technique can in many cases offer superior labelling quality.