title: The characteristic cellular organization and CEACAM1 expression in the junctional epithelium of rats and mice are genetically programmed and not influenced by the bacterial microflora.
abstract: BACKGROUND
  The epithelial cell adhesion molecule CEACAM1 exhibits an interesting dynamic expression during tooth development. It is first expressed in the reduced enamel epithelium, its expression then increases in the orally faced reduced epithelium and the overlying oral epithelium that then fuse to give rise to the junctional epithelium. The expression of CEACAM1 remains at high levels in the junctional epithelium, in contrast to the surrounding oral sulcular epithelium which shows much lower expression levels. We investigated if the high expression levels of CEACAM1 and the loosely organized cells characteristic of the junctional epithelium are genetically programmed or result from bacterial infiltration.
  
  
  METHODS
  Oral tissues from germ-free rats and mice and animals with conventional bacterial flora were analyzed by transmission electron microscopy and immunohistochemical staining for CEACAM1.
  
  
  RESULTS
  The junctional epithelium of both germ-free and conventional animals was identical with respect to both CEACAM1 expression and morphology. Also the presence of leukocytes was the same in both types of animals.
  
  
  CONCLUSIONS
  The results indicate that the characteristic morphology and the high expression levels of CEACAM1 in the junctional epithelium are genetically programmed and not a result of bacterial infiltration. This suggests that CEACAM1 has an important role for the structural integrity of the junctional epithelium. This conclusion was supported by the observation that the junctional epithelium does not express any E-cadherin, which is another abundant epithelial cell adhesion molecule.
authors.affiliation: Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Heymann
authors.forename: J
authors.initials: J
authors.lastname: Wroblewski
authors.forename: C
authors.initials: C
authors.lastname: Terling
authors.forename: T
authors.initials: T
authors.lastname: Midtvedt
authors.forename: B
authors.initials: B
authors.lastname: Obrink
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000032:analysis / Q000235:genetics*; D000943:Antigens, Differentiation / Q000032:analysis / Q000235:genetics*; D018407:Bacterial Physiological Phenomena; D015820:Cadherins / Q000032:analysis / Q000235:genetics; D002272:Carcinoembryonic Antigen; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D004396:Coloring Agents; D003743:Dental Enamel / Q000166:cytology / Q000378:metabolism; D004195:Disease Models, Animal; D004846:Epithelial Attachment / Q000166:cytology / Q000378:metabolism* / Q000382:microbiology; D004847:Epithelial Cells / Q000378:metabolism; D000939:Epitopes / Q000032:analysis / Q000235:genetics*; D015870:Gene Expression; D005856:Germ-Free Life; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D009061:Mouth Mucosa / Q000166:cytology / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; C069847:CD66 antigens; D015820:Cadherins; D002272:Carcinoembryonic Antigen; C486183:Ceacam1 protein, mouse; D015815:Cell Adhesion Molecules; D004396:Coloring Agents; D000939:Epitopes