Patterns of epithelial cells in the marginal mucosa of an active ulcer. (a) An H&E-stained section taken at 1 week after acetic acid treatment, showing a crater of granulation tissue and marginal tissue surrounding the crater. Scale: 1000 μm. (b) A magnified view of the ulcer margin mucosa outlined in (a). Scale: 100 μm. (c-h) Serial sections of (b) stained with MUC5AC (c), TFF2 (d), MUC6 (e), pepsinogen II (f), H+/K+-ATPase (g), and PCNA (h). (i-k) Double-color immunostaining for DCAMKL1 with MUC5AC (i), DCAMKL1 with TFF2 (j), and PCNA with TFF2 (k). Scales: 100 μm. (l) Double-color immunostaining for DCAMKL1 with PCNA. Scale: 10 μm. The inset in (h-k) shows a magnified view of the outlined area.