Ultrastructural appearance of red cells frozen with glycerol for clinical use

Freeze-fracture replicas prepared from full units of red cells frozen with glycerol under clinical conditions suggest that the cells are found in a concentrated glycerol phase and so are physically separated from the extracellular ice which formed during freezing. The cells possess a relatively smooth cytoplasmic surface with no evidence of intracellular ice. Half-membrane views of PF faces indicate that the intramembrane particles are aggregated.