Figure 1 Haematoxylin and eosin staining (A, G), and expression of KL‐6 (B–E, red) and Ki‐67 (F, L) in the human pterygium head (A–F) and body (G–L). KL‐6 immunoreactivity is detected in the pterygium tissue (B–D). At high magnification, immunoreactivity for KL‐6 is located in the cytoplasm and on the cell membrane of many epithelial cells (E). KL‐6 expression is not detected in superficial cells (E, arrows), nor in the basement membrane (C–E, arrows). Immunoreactivity for KL‐6 is strongly noted in pterygium body epithelium (H–J), especially in the cytoplasm (K). Nuclear immunoreactivity for Ki‐67 is detected in several pterygium epithelial cells (F, L). Green: nuclear staining with YO‐Pro‐1. Bar  =  50 μm.