MECHANICAL FORCES AS A CAUSE OF CELLULAR DAMAGE BY FREEZING AND THAWING

¹ Institute for Experimental Medical Research, Ullevaal Hospital, Oslo, Norway

1 . The present investigation was initiated in an attempt to dissociate two potential factors in cellular injury from freezing and thawing: damage due to mechanical forces attendant upon ice crystal formation and damage due to physical and chemical changes associated with withdrawal of water.

2. Red blood cells in diluted blood from the congo eel were covered and subjected to microscopic examination during freezing induced by a piece of solid carbon dioxide placed at the edge of the coverglass. Ice crystals grew into the preparation, first rapidly and then more slowly the further from the piece of solid carbon dioxide they advanced. The sequence of events as observed through the microscope was different for different freezing velocities.

3. Rapid freezing caused intracellular ice formation and this internal freezing was always associated with hemolysis even if followed by immediate thawing. At slow freezing the cells became dehydrated without any signs of intracellular ice formation. Such cells would recover if thawing occurred within a few seconds, but they were all hemolyzed after prolonged exposure.

4. It is concluded that, dependent on the freezing rate, either mechanical forces or physical and chemical factors may be the main cause of cellular damage from freezing, the mechanical forces being predominant at rapid freezing.

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