title: Organic content in occlusal groove-fossa-system in unerupted 3rd mandibular molars: a light and electron microscopic study.
abstract: A method is described by means of which organic content in fissure areas of 12 unerupted 3rd mandibular molars can be prepared for studies in the light microscope (LM) and in the transmission electron microscope (TEM). Thus, LM and TEM examinations revealed that the organic content throughout the fissure in bone-covered and in mucosa-covered 3rd molars with uncompleted root formation consists of cells belonging to the enamel organ in late or in postmaturative stages. In mucosa-covered teeth with completed root formation it was only possible to identify enamel organ cells at the entrance of the fissure. Deeper parts were occupied by degenerative cells, polymorphonuclear cells and unidentified material. The results indicate that ameloblasts in fissures do not transform to stratified squamous epithelium but gradually degenerate towards terminal stages and remain as such, as the tooth emerges into the oral cavity.
authors.affiliation: Department of Cariology and Endodontics, Royal Dental College, Copenhagen, Denmark.
authors.forename: K R
authors.initials: KR
authors.lastname: Ekstrand
authors.forename: J
authors.initials: J
authors.lastname: Westergaard
authors.forename: A
authors.initials: A
authors.lastname: Thylstrup
mesh_terms: D000293:Adolescent; D000328:Adult; D000565:Ameloblasts / Q000166:cytology / Q000648:ultrastructure; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D003743:Dental Enamel / Q000033:anatomy & histology* / Q000166:cytology / Q000648:ultrastructure; D004847:Epithelial Cells; D004848:Epithelium / Q000648:ultrastructure; D006801:Humans; D008247:Lysosomes / Q000648:ultrastructure; D008854:Microscopy, Electron; D008964:Molar, Third / Q000033:anatomy & histology* / Q000648:ultrastructure; D009805:Odontogenesis; D014092:Tooth Root / Q000033:anatomy & histology; D014097:Tooth, Unerupted / Q000033:anatomy & histology* / Q000648:ultrastructure