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A quantitative histological analysis of the dilated ureter of childhood
B R Lee1, A W Partin, J I Epstein
1Department of Urology, James Buchanan Brady Urological Institute, Johns Hopkins Hospital, Baltimore, Maryland 21205.
Insights
Pediatric megaureters show distinct collagen and smooth muscle differences. Refluxing megaureters have significantly more collagen and less smooth muscle than obstructed types, impacting surgical repair insights.
Area of Science:
- Pediatric Urology
- Histology
- Biomaterials Science
Background:
- Dilated ureters in children (megaureters) present diagnostic and therapeutic challenges.
- Understanding the structural composition of megaureters is crucial for effective surgical management.
- Previous studies have not fully elucidated the quantitative differences in extracellular matrix components between different types of pediatric megaureters.
Purpose of the Study:
- To quantitatively compare the collagen and smooth muscle content in the muscularis layers of primary obstructed and primary refluxing megaureters in children.
- To compare these components to normal control ureters.
- To provide insights into the pathological basis of different megaureter types and inform surgical repair strategies.
Main Methods:
- Quantitative histological analysis of 26 pediatric megaureter specimens (15 male, 11 female; age 10 days to 12 years).
- Color image analysis system used to measure collagen and smooth muscle percentages in the muscularis layer.
- Comparison of primary obstructed (n=12), primary refluxing (n=14), and control (n=6) ureters.
Main Results:
- A statistically significant difference in the collagen-to-smooth muscle ratio was found between primary obstructed and primary refluxing megaureters (p < 0.001).
- Refluxing megaureters exhibited a 2-fold higher collagen-to-smooth muscle ratio compared to obstructed megaureters.
- Refluxing megaureters showed significantly decreased smooth muscle (40% +/- 5%) and increased collagen (58% +/- 5%) compared to obstructed megaureters (60% +/- 5% smooth muscle, 36% +/- 5% collagen) and controls (61% +/- 6% smooth muscle, 30% +/- 5% collagen).
Conclusions:
- Significant structural differences exist in the collagen and smooth muscle composition of pediatric megaureters based on etiology.
- Primary refluxing megaureters are characterized by increased collagen and decreased smooth muscle, suggesting a distinct pathological process.
- These findings offer valuable insights into the pathophysiology of pediatric megaureters, aiding in the development of targeted surgical approaches.
Abstract:
A quantitative histological study of the dilated ureter of childhood was performed on 26 ureters. The specimens were from 15 male and 11 female patients 10 days to 12 years old (mean age 2.0 years). A color image analysis system was used to examine and compare collagen and smooth muscle components of the muscularis layers to normal control ureters of similar age. In comparing primary obstructed (12) to primary refluxing (14) megaureters and control ureters (6), there was a statistically different collagen-to-smooth muscle ratio (p < 0.001) between the primary obstructed and primary refluxing megaureter groups. For patients with primary refluxing megaureter there was a 2-fold increase in the tissue matrix ratio of collagen-to-smooth muscle when compared to patients with primary obstructed megaureter. In the primary obstructed megaureters the amount of collagen and smooth muscle was not statistically different from controls (p > 0.01). The increased tissue matrix ratio of 2.0 +/- 0.35 (collagen-to-smooth muscle) in the refluxing megaureter group compared to 0.78 +/- 0.22 in the obstructed megaureter group and 0.52 +/- 0.12 in controls was found to be due not only to a marked increase in collagen but also a significant decrease in the smooth muscle component of the tissue. Primary obstructed and normal control ureters had similar quantitative amounts of smooth muscle with 60 +/- 5% and 61 +/- 6%, respectively, while refluxing megaureters had only 40 +/- 5% smooth muscle. The percentage collagen was 36 +/- 5 in the obstructed megaureter group and 30 +/- 5 in controls, with refluxing megaureters having 58 +/- 5% collagen on analysis. Our findings emphasize the significant differences in the structural components (collagen and smooth muscle) of the dilated ureter of childhood, and provide us with further insight into the pathological nature of these dilated ureters and their surgical repair.