INVESTIGATIVE UROLOGY

An Electron Microscopic Examination of the Intravesical Ureter in Children with Primary Vesico-Ureteric Reflux
Sofikerim M, Sargon M, Oruc O, Dogan HS, Tekgul S
Department of Urology, Hacettepe University, Faculty of Medicine, Ankara, Turkey
BJU Int. 2007; 99: 1127-31

• Objective: To determine the structure of the intravesical distal ureteric wall of patients with primary vesico-ureteric reflux (VUR), and to compare the findings with previous reports.
• Materials and Methods: Specimens of the distal intravesical ureteric segments were taken surgically from children undergoing ureteric reimplantation surgery for primary VUR. There were 24 distal intravesical ureteric specimens from 15 children (nine female and six male). Ultra-thin sections were cut from the specimens and examined with a transmission electron microscope.
• Results: The appearance of the muscular layers of the specimens of different grades differed markedly. There were intercellular oedematous areas in the muscular layer in specimens from patients with grade 2 and 3 VUR. In specimens from grade 4 VUR there were also intracytoplasmic vacuoles in the smooth muscle cells. The most marked and striking changes were in the specimens from children with grade 5 VUR, in which there were large intercellular oedematous areas and prominent large intracytoplasmic vacuoles.
• Conclusion: Refluxing ureters differ from normal ureters in having disorganized smooth muscle fibres and altered smooth muscle cell structure, leading to incompetence of the valve mechanism. Although we cannot confirm that these pathological changes in the smooth muscle layer of the intravesical ureteric wall are caused by VUR we conclude that, with increasing degrees of reflux, the degree of smooth muscle damage increases, and that the rate of spontaneous resolution decreases.
  
  
• Editorial Comment
  The authors taken specimens of intravesical distal ureteric segments surgically removed from children undergoing ureteric reimplantation due to primary vesicoureteral reflux (VUR) of different degrees. They studied by histological methods and for the first time by transmission electron microscopy (TEM), the structure and structural changes of the specimens. The results were compared with controls and with the grades of VUR.
  The authors found no marked differences in the morphology of the tunica adventitia, and no pathology was detected. The structure and distribution of collagen fibers, fibrocytes and fibroblasts in the adventitia were similar in all specimens. The transitional epithelial cells were closely arranged in the tunica mucosa and the submucosa contained collagen fibers, fibrocytes and fibroblasts in variable proportions. Further, the morphology of the lamina propria and the tunica mucosa were similar in all specimens, and no ultrastructural change or pathology was detected.
  On the other hand, the findings demonstrated that the appearance of the muscular layers of the specimens differed markedly with VUR grade. The distribution of intracytoplasmic vacuoles in smooth muscle cells and intercellular edema are clearly shown by semi-quantitative methods. Intercellular edema was sparse in specimens of grade 2–3 VUR, moderate in specimens of grade 4 and common in specimens of grade 5. Intracytoplasmic vacuoles were absent in specimens of grade 2–3 VUR, sparse in grade 4 and common in grade 5.

Dr. Francisco J.B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, RJ, Brazil
sampaio@urogenitalresearch.org