title: [Histology and proliferative capability of thoracic vertebral body growth plates of rats at different ages].
abstract: OBJECTIVE
  To compare the histological features of the thoracic vertebral body growth plates (VBGPs) of rats at different ages and assess their proliferative capability.
  
  
  METHODS
  The thoracic VBGPs obtained from rats aged 1 day and 1, 4, 8, 16 and 28 weeks were identified using safranin O-fast green staining, and the height of the hypertrophic zone, proliferative zone, and resting zone were measured. The chondrocytes were isolated from these VBGPs with a modified trypsin-collagenase type II digestion method for primary culture in vitro. The expressions of proliferating cell nuclear antigen (PCNA) mRNA and protein was detected by real time-PCR and Western blotting, respectively.
  
  
  RESULTS
  The 1-day- and 1-week-old rats showed significantly greater hypertrophic zone and proliferative zone in the VBGPs than older rats (P<0.01); the proliferative zone was significantly greater in rats aged 4 weeks than in those aged 28 weeks (P<0.05). The resting zone was obviously greater in rats aged 1 day and 1 week than in older rats (P<0.05), and also greater in rats aged 4 weeks than in those aged 16 and 28 weeks (P<0.05). Obvious ossification in the resting zone occurred at 16 weeks, and most of the resting zone became ossified at 28 weeks. The expression of PCNA decreased at both the mRNA and protein levels as the rats grew.
  
  
  CONCLUSIONS
  The 3 zones of VBGPs are greater in rats aged 1 day and 1 week than in older ones. Ossification in the resting zone begins at 16 weeks, and till 28 weeks, most of the resting zone is ossified. The proliferation ability of VBGP chondrocytes decreases with the increase of age of the rats.
authors.affiliation: Department of Orthopedic and Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. litao1981839@126.com
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Jian-ting
authors.initials: JT
authors.lastname: Chen
authors.forename: Qing-an
authors.initials: QA
authors.lastname: Zhu
authors.forename: Zi-xing
authors.initials: ZX
authors.lastname: Xu
authors.forename: Ding-sheng
authors.initials: DS
authors.lastname: Zha
authors.forename: Fu-qiang
authors.initials: FQ
authors.lastname: Liu
authors.forename: Song-hui
authors.initials: SH
authors.lastname: Wu
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.forename: Wen-de
authors.initials: WD
authors.lastname: Xiao
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D049109:Cell Proliferation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology*; D006132:Growth Plate / Q000033:anatomy & histology* / Q000166:cytology; D008297:Male; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013904:Thoracic Vertebrae / Q000254:growth & development*
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger