OTO method for preservation of actin filaments in electron microscopy.

Osmium tetroxide, commonly used as a fixative in electron microscopy, can destroy actin filaments. Thiocarbohydrizide (TCH) is a bipolar substance that binds to the osmium. By sandwiching TCH between two phases of osmium treatment, tissue exposure to osmium could be minimized without destroying actin filaments. The contrast of osmophilic components of cells was also enhanced.