The defence architecture of the superficial cells of the oral mucosa

Abstract The oral epithelium together with the saliva and its components forms a complex structure which is the first line of defence in the oral cavity. The surface of superficial cells of the oral epithelium contains ridge-like folds, microplicae (MPL), which are typical of the surfaces of areas covered with protective mucus. The role of MPL seen on the upper surface of the oral epithelial cells is still unknown. The salivary mucus gel performs a protective diffusion membrane against harmful substances and this membrane is built up by epithelial cells covered by a highly hydrated and viscous gel, where mucins constitute the scaffold. The interaction between the MPL-structure and the mucins is shown in cornea, so that mucins are expressed on the tips of the MPL of the epithelial cells. We hypothesized that the MPL architecture of oral superficial epithelial cells provides the underlying basis for mucins’s protective function as well as in ocular surface. The salivary mucous barrier is required to protect the superficial cells and the MPL-structure together with membrane anchored mucin binding protein (MBP) forms the ground to this mucous barrier. So, oral mucosal barrier complex (OMBC) contains both the MBP-mucin – complex and the MPL-structure of the superficial cells. In the future, studies of the alterations of the salivary mucins and that of the MPL-structure may yield therapeutic opportunities for burning mouth syndrome and perhaps for mucositis causing by irradiation. Focus on cell surface microplication and mucins in oral mucosal biology and oral mucosal diseases is a promising avenue for future research in several ways.