Ultrastructural Changes in the Rat Corneal Endothelium Preserved at Low Temperature

The ultrastructural differences in rat corneal endothelia preserved at 0°C and 4°C were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Some corneas were preserved as whole globes in an eye preservation medium (EP-II) either at 4°C or at 0°C for 1, 2 and 7 days. The specimens were prepared for SEM and TEM according to routine methods. For all storage times, the endothelium preserved at 0°C showed less irregularity of the cell surface, swollen mitochondria or vacuoles than that at 4°C. A significant difference in structural changes between the endothelium preserved at 4°C and 0°C was seen after 7 days' storage. The former showed destruction of the surface cell membrane and degenerated cell organella, while the latter maintained the structure of the surface cell membrane and cell organella. These findings suggest that the lifetime of a rat endothelium preserved at 0°C is longer than that at 4°C.