Figure 3. Hematoxylin and eosin staining of porcine corneal stroma. The porcine cornea stroma were stained before treatment (A) as well as after incubating for one week in N₂ gas (B), in air without freezing (C), or in air after freezing (D). Hematoxylin and eosin staining showed few cellular nuclei in the corneal stroma of the N₂ group on day 7 whereas many nuclei were observed in the corneal stroma of control groups 1 and 2 on day 7. All figures are at the same magnification, and the bar is 100 µm.