Freeze fracture electron microscopy of a cryopreserved human oocyte. The cryoprotectant used was propanediol (1.5M) + sucrose (0.1M) + serum (20%). Oocytes were placed in a small droplet on a fragment of coverslip which was cooled on the sample plate of an Asymptote freezer. Ice was nucleated in the droplet at -7°C. The sample was then cooled at 0.3°C per minute to -30°C and then transferred to liquid nitrogen. Deep etching of the coverslip removes ice and reveals a highly shrunken oocyte, which has shrunken in a non spherical manner.