title: Expression of Ki-67, Oct-4, γ-tubulin and α-tubulin in human tooth development.
abstract: OBJECTIVE
  To analyze factors controlling cell proliferation and differentiation, and appearance of primary cilia during the cap and bell stages of incisor or/and canine human enamel organs.
  
  
  METHODS
  Qualitative and quantitative analysis of proliferating Ki-67 positive cells and expression of γ-tubulin, α-tubulin and Oct-4 was immunohistochemically analyzed in the cap an bell stages of 10 developing human incisor and canine germs, 8-21 weeks old.
  
  
  RESULTS
  During the analyzed period, ratio of Ki-67 positive cells changed in outer enamel epithelium from 48.86% to 24.52%, in inner enamel epithelium increased from 56.11% to 60.06% and then dropped to 44.24%. While in dental papilla proliferation first increased from 46.26% to 55.45%, and then dropped to 22.08%, a constant decrease of proliferation characterized enamel reticulum (from 46.26% to 15.49%). Strong cytoplasmic Oct-4 expression characterized epithelial parts of enamel organ, particularly the differentiating ameloblasts. During further development, Oct-4 expression shifted to both nuclear and cytoplasmic expression in mesenchymal tooth components. Primary cilia characterized most of the cells in developing enamel organ. While non-ciliated (proliferating) cells mainly contained two centrioles (γ-tubulin), the primary cilia (α-tubulin) were arising from basal bodies (γ-tubulin) of non-proliferating cells.
  
  
  CONCLUSIONS
  We suggest that increase in cell proliferation enables growth of enamel organ, while its selective decrease leads to disintegration of some tooth parts. Drop of proliferation coincided with initiation of ameloblast and odontoblast differentiation. Additionally, cell differentiation was accompanied by increased expression of Oct-4 and probably by signalling via primary cilia, both regulating processes of cell proliferation and differentiation.
authors: School of Dental Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
authors: Darko
authors: D
authors: Kero
authors: Department of Histology and Embryology, School of Medicine University of Mostar, Bijeli brijeg bb, 88000 Mostar, Bosnia and Herzegovina.
authors: Josip
authors: J
authors: Novakovic
authors: Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
authors: Katarina
authors: K
authors: Vukojevic
authors: Department of Pathology, School of Medicine, University of Mostar, Bijeli brijeg bb, 88000 Mostar, Bosnia and Herzegovina.
authors: Josko
authors: J
authors: Petricevic
authors: School of Dental Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
authors: Danijela
authors: D
authors: Kalibovic Govorko
authors: School of Dental Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
authors: Dolores
authors: D
authors: Biocina-Lukenda
authors: Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia. Electronic address: msb@mefst.hr.
authors: Mirna
authors: M
authors: Saraga-Babic
mesh_terms: D000565:Ameloblasts / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D003743:Dental Enamel / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000378:metabolism*; D050814:Octamer Transcription Factor-3 / Q000378:metabolism*; D009805:Odontogenesis / Q000502:physiology*; D014070:Tooth / Q000196:embryology* / Q000378:metabolism*; D014083:Tooth Germ / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*
chemical_list: D019394:Ki-67 Antigen; D050814:Octamer Transcription Factor-3; D014404:Tubulin
keywords: Differentiation; Human tooth development; Ki-67; Oct-4 protein; α-Tubulin; γ-Tubulin