Fig. 5

a-d Representative transmission electron microscopy (TEM) images of the conjunctiva and e-h scanning electron microscopy (SEM) images of the cornea on day 7. a,e: control group, b,f: 1-min PI group, c,g: 3-min PI group, d,h: 10-min PI group. TEM images revealing the conjunctival epithelial ultrastructure (a-d). Abundant microvillar structures on the surfaces of conjunctival epithelial cells (arrowhead) and goblet cells with many secretory granules (arrow) are observed in the control and 1-min PI group (a, b), whereas the extent of microvillar structure decreased, and apoptotic morphological changes (including nuclear fragmentation, condensation, and peripheral migration of chromatin) were shown in the other groups (c, d). (Bar: 2 μm). SEM images revealing the corneal epithelial structure (e-h). The superficial cells were intact with normal microvilli in the control group (e), whereas the flat surfaces with destroyed microvilli were shown in the all three PI groups. The longer the exposure time, the greater was the reduction in the number of microvilli (black arrow) (f-h)