title: Microstructure of oral epithelial cells as an underlying basis for salivary mucosal pellicle.
abstract: BACKGROUND
  Salivary mucosal pellicle forms the structural basis of the local innate immune defense mechanism of the oral mucosa. At the surface of the oral mucosa, the apical cell membrane adjacent to the saliva interface contains short membrane folds, termed microplicae (MPL). This MPL structure of oral epithelial cells and its function as a basis to the salivary mucosal pellicle is unclear. In this preliminary study, we describe the ultrastructural morphology of cell membrane of superficial cells of the oral mucosa and study the membrane-associated mucins (MAMs), MUC1 and MUC4, with immunohistological methods.
  
  
  METHODS
  Oral mucosal specimens were obtained from six healthy patients. Half of each specimen was prepared routinely for light microscopy, and the other part for scanning and transmission electron microscopy. The presence of MUC1 and MUC4 were studied by immunohistochemical methods in oral mucosal specimens.
  
  
  RESULTS
  Morphologically, the cell membrane of MPL is partly discontinuous and membrane-associated molecules extrude from the cell membrane. MUC1 expression was detected in the superficial part of the buccal epithelium, while MUC4 had no expression in the oral squamous epithelium.
  
  
  CONCLUSIONS
  The novel of this study is that the membrane-tethered molecules seem to occur onto the cell membrane of the superficial epithelial cells of the oral mucosa. Furthermore, the stratified squamous epithelium of the buccal mucosa produces MUC1 for the surface-saliva pellicle interface. The interaction between MPL structure, MUC1 mucin, and salivary mucosal pellicle is discussed.
authors: Department of Oral Diagnostic Sciences, Institute of Dentistry, University of Eastern Finland , Kuopio Campus, Kuopio , Finland .
authors: Arja M
authors: AM
authors: Kullaa
authors: Pekka
authors: P
authors: Asikainen
authors: Maria
authors: M
authors: Herrala
authors: Helena
authors: H
authors: Ukkonen
authors: Jopi J W
authors: JJ
authors: Mikkonen
mesh_terms: D000328:Adult; D044622:Dental Pellicle / Q000378:metabolism / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D009061:Mouth Mucosa / Q000378:metabolism / Q000648:ultrastructure*; D018396:Mucin-1 / Q000096:biosynthesis; D055264:Mucin-4 / Q000096:biosynthesis
chemical_list: C060192:MUC1 protein, human; C524658:MUC4 protein, human; D018396:Mucin-1; D055264:Mucin-4
keywords: MUC1; MUC4; Microplicae; mucins; oral mucosa; saliva; scanning electron microscopy; transmission electron microscopy