Freeze fracture electron microscopy of a solution used for mouse sperm cryopreservation in a straw (0.25ml capacity). The sample was frozen by a standard vapour freezing technique, no seeding was applied and it is likely that extensive supercooling would have occurred. 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).
