title: Serial microscopic changes in cell proliferation and apoptosis in obstructed ureter of rat.
abstract: OBJECTIVE
  We investigated the histologic findings and serial changes in cell proliferation and apoptosis in obstructed rat ureters.
  
  
  METHODS
  After unilateral ligation of the ureter, animals from each of five groups of Sprague- Dawley rats were sacrificed for examination at 1, 5, 10, 15, 20, 25, 30, or 35 days. Cell division was detected with proliferating cell nuclear antigen (PCNA) immunohistochemistry, and apoptosis was detected with terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) in-situ nick-end labeling (TUNEL) study.
  
  
  RESULTS
  The epithelial layer was thickened in 5-day-obstructed ureters (5 DOUs). The severity of thickening of the fibrous and smooth-muscle layers progressed consistently to 15 DOUs and were maintained in 35 DOUs. Expression of PCNA in the epithelial layer was present in every ureter, and a significant increase in the number of labeled cells was present in 1 and 5 DOUs. Expression of PCNA in the fibrous and smoothmuscle layers was detectable in 10 DOUs and was maintained in 20 DOUs, after which, it declined significantly in the 25 DOUs. TUNEL-positive cells in the epithelial layer were shown in 10, 15, 20, 25, 30, and 35 DOUs, with the peak being reached at 25 days. TUNEL-positive cells in the fibrous and smooth-muscle layers were found in 25, 30, and 35 DOUs.
  
  
  CONCLUSIONS
  Cell proliferation and apoptosis may play an important role in the pathogenesis of damage in obstructed ureters. Peak times of proliferation and apoptosis were different in the epithelial and fibrous and smooth-muscle layers.
authors.affiliation: Department of Urology, Konkuk University College of Medicine, Seoul, Korea.
authors.forename: Hyeong Gon
authors.initials: HG
authors.lastname: Kim
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Paick
authors.forename: Chul
authors.initials: C
authors.lastname: Kwak
authors.forename: Hyeon Hoe
authors.initials: HH
authors.lastname: Kim
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Lho
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D049109:Cell Proliferation; D020287:In Situ Nick-End Labeling; D009130:Muscle, Smooth / Q000473:pathology; D018809:Proliferating Cell Nuclear Antigen; D051381:Rats; D017207:Rats, Sprague-Dawley; D014517:Ureteral Obstruction / Q000473:pathology / Q000503:physiopathology*; D019459:Urothelium / Q000473:pathology
chemical_list: D018809:Proliferating Cell Nuclear Antigen