title: [The effect of the structure of epithelial root sheath on the development of tooth root].
abstract: OBJECTIVE
  To investigate the effect of the structure of epithelial root sheath (ERS) on the development of tooth root.
  
  
  METHODS
  The first molars of postnatal (PN) 8 d SD rats were chosen to harvest the apical tissue. The tissues were digested by the mixture of type I collagenase and dispase. One part of the cell suspension was pelleted by centrifugalization. The other part of the cell suspension was digested by trypsin and then pelleted. The cell pellets were cultured in vitro for 4 hours and then implanted into renal capsule of the mother rats.
  
  
  RESULTS
  It was found that ERS was dissociated into fragments by the mixture of type I collagenase and dispase or single cells by trypsin. The pellets containing fragments of ERS generated tooth root-like structure and periodontal tissues. The pellets containing single cells of ERS formed tubular and bone-like dentin.
  
  
  CONCLUSIONS
  The bilayered epithelial structure of ERS has important role in the development of tooth root.
authors.affiliation: Department of Stomatology, the General Hospital of Lanzhou Command. Lanzhou 730050;China.E-mail:statue0000@126.com.
authors.forename: Xiao-hui
authors.initials: XH
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Yuan
authors.forename: Yi-nong
authors.initials: YN
authors.lastname: Qiu
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
mesh_terms: D000818:Animals; D003804:Dentin; D008963:Molar; D051381:Rats; D017207:Rats, Sprague-Dawley; D019227:Tooth Apex; D014092:Tooth Root