title: [Occurrence of supernumerary upper incisor teeth in Pax6-/- mouse fetuses].
abstract: OBJECTIVE
  To investigate the occurrence of supernumerary upper incisor teeth in Pax6-/- mouse fetuses and to provide a model to explore the role of Pax6 in the upper incisor development and the mechanism of supernumerary teeth involving Pax6.
  
  
  METHODS
  Twenty Pax6-/- mouse fetuses of strain DEBA were isolated on E18.5 (embryonic day). The fetuses were sectioned serially in coronal plane and stained with haematoxylin and erosion, then the presence of supernumerary teeth in the upper anterior area was examined histologically, and also the number, morphology and structure of lower incisor germs and the first and second molar germs in the maxilla and mandible were observed histologically. Eighteen E18.5 mouse fetuses of strain DEBA with Pax6+/+ genotype were used as control.
  
  
  RESULTS
  Of the 20 Pax6-/- fetuses examined, four possessed a single supernumerary tooth in the upper incisors' region. No supernumerary upper incisor teeth were observed in any of the 18 Pax6+/+ fetuses examined. In the regions of lower incisors and the first and second molars of the maxilla and mandible, no significant difference was observed between Pax6-/- and Pax6+/+ fetuses regarding the number, morphology and structure of tooth germs.
  
  
  CONCLUSIONS
  The results suggest that Pax6 played an important role in the development of upper incisor teeth in mice.
authors.affiliation: Peking University Stem Cell Research Center, Beijing 100081, China.
authors.forename: Hai-hua
authors.initials: HH
authors.lastname: Lei
authors.forename: He
authors.initials: H
authors.lastname: Liu
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Jin-hua
authors.initials: JH
authors.lastname: Wen
authors.forename: Li-hong
authors.initials: LH
authors.lastname: Ge
mesh_terms: D000818:Animals; D005136:Eye Proteins / Q000235:genetics*; D005333:Fetus; D018398:Homeodomain Proteins / Q000235:genetics*; D007180:Incisor / Q000196:embryology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D014083:Tooth Germ / Q000254:growth & development; D014096:Tooth, Supernumerary / Q000235:genetics*
chemical_list: D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins