Freeze fracture electron microscopy of an aqueous solution of glycerol (10%) frozen in a straw (0.25ml capacity). Ice was nucleated within the straw at -7°C, the sample was then cooled at c.1000°C per minute to -100°C and then transferred to liquid nitrogen. A cross fracture of the straw followed by deep etching reveals the structure of ice (etched areas) and of the freeze concentrated material (non-etched material). The freeze concentrated material is not homogeneous in composition and contains many small ice crystals. Detail from a cross fracture of a whole straw
