Figure 3

The expression of pK in keratinocytes and K20 in Merkel cells and the localization of NF200 in nerve fibres of the lesional human oral mucosa of hyperkeratosis. (a and b) In hyperkeratosis, the numerous great oval basal epithelial cell extensions at the basal cell layer are identified by H&E staining (b = detail of the squared area in a). (c) Except for in the basal layer, keratinocytes and Merkel cells stain positively for pK. (d) Merkel cells distributed in the basal layer are strongly ir for K20. (e) NF200-ir is not detectable in the nerve fibres of the lesional epithelium of hyperkeratosis. (f) NF200 is identified only in single nerve fibres in the lamina propria (asterisks). (g) NF200-ir nerve fibres and nerve endings are not detected in relation to K20-ir Merkel cells of the lesional oral mucosal epithelium of hyperkeratosis. (h) Compared with healthy oral mucosa, lesional oral mucosa of hyperkeratosis is associated with a significantly decreased number of NF200-ir nerve fibres. Bars: a = 1 mm; b–f = 50 µm, g = 20 µm. bl, basal layer; H&E, hematoxylin and eosin; ir, immunoreactive; K20, cytokeratin 20; lp, lamina propria; NF200, neurofilament 200; ome, oral mucosal epithelium; pK, pan cytokeratin.