Figure 1

The expression of pK in keratinocytes and K20 in Merkel cells and the localization of NF200 in nerve fibres of healthy human oral mucosa. (a) In the healthy oral mucosal epithelium, pK is detected with different staining intensities (dependent on the epithelial layer) in keratinocytes and in Merkel cells of the oral mucosal epithelium. (b) K20 is identified only in Merkel cells located at the basal layer of the epithelium. (c and d) NF200 is located in nerve fibres and nerve endings distributed in the intraepithelial area (one asterisk), in the basal layer of the epithelium (two asterisks) and in the lamina propria of the healthy oral mucosa. (e) DRAQ5 (chromosome marker) is identified in cell nuclei of the keratinocytes (blue). Intraepithelial NF200-ir nerve fibres (green) are detected in association (yellow) with the K20-ir Merkel (red) cells at the basal layer of the epithelium. Note that some intraepithelial NF200-ir nerve fibres are not associated with the Merkel cells (arrows). Bars: a–d = 50 µm; e = 10 µm. bl, basal layer; ir, immunoreactive; K20, cytokeratin 20; lp, lamina propria; NF200, neurofilament 200; ome, oral mucosal epithelium; pK, pan cytokeratin.