Cytokeratin 20-positive Merkel Cells in Human Gingival Epithelium

Objectives: Merkel cells are present in the basal layers of stratified squamous epithelia, but their proximity to myelinated nerves has prompted the belief that they have a sensory receptor function. Previous studies have localised oral epithelial Merkel cells to keratinised sites only. This study aimed to refine this by analysing the density of cytokeratin (CK) 20-positive Merkel cells in mandibular and maxillary gingiva. Methods: 102 wax-embedded, archival, autopsy gingival specimens from 70 humans (45 males, 25 females, age range 42-92 years, mean 70.1, 47 maxillary samples, 55 mandibular) were analysed. 24 individuals had remaining teeth in at least one jaw, the remainder were edentulous. 5 µm sections were stained with a monoclonal antibody to CK20 (Dako) using standard immunoperoxidase or immunoalkaline phosphatase methods. Positive cells were counted in 20 high power fields in three sections from each biopsy, and analysis of variance calculated for differences related to age, sex, site and presence of teeth. Results: CK20+ Merkel cells were present either singly, or in clusters, in the basal epithelial layers, particularly at the tips of rete ridges. Mean numbers of gingival Merkel cells were significantly higher (p<0.05) in edentate (1.39 cells per field) when compared to dentate (0.67) individuals. The differences were not statistically significant for any other variable. Conclusion: the data raise the possibility that reduced proprioception following loss of teeth is compensated for by an increase in the local Merkel cell population.