Freeze fracture electron microscopy of a suspension of the unicellular green alga Euglena gracilis cryopreseved in a straw (0.25ml capacity). The cryoprotectant used was methanol (10% v/v). Ice was nucleated within the straw at -7.5°C, the sample was then cooled at 0.5 °C per minute to -100°C and then transferred to liquid nitrogen. A cross fracture of the straw followed by deep etching reveals a band of cells which presumably have been excluded from ice crystals. These cells are not significantly shrunken. The methanol employed as cryoprotectant sublimates along with ice during etching and it is not possible to distinguish the ice structure.

Low power. For higher magnifications of this sample see the next pages.