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A quantitative study of smooth muscle cells in reflux, obstructed, and triad bladders. A preliminary report;
Insights
Bladder smooth muscle cell size increases with age, indicating outflow obstruction. This finding is measurable in biopsies, offering clinical utility for diagnosing bladder conditions.
Area of Science:
- Urology
- Developmental Biology
- Pathology
Background:
- Bladder smooth muscle cell size changes with age and obstruction.
- Understanding cellular changes is crucial for diagnosing bladder dysfunction.
Purpose of the Study:
- To investigate the relationship between vesical smooth muscle cell size and age.
- To determine if cell size changes correlate with bladder outflow obstruction or other conditions.
- To assess the clinical applicability of measuring cell size for diagnosing obstruction.
Main Methods:
- Quantitative analysis of vesical smooth muscle cell and nuclear size in human bladder specimens.
- Correlation of cell size with patient age and clinical diagnoses (outflow obstruction, vesicoureteral reflux, congenital anomalies).
Main Results:
- Average vesical smooth muscle cell size increases with age; nuclear size remains constant.
- Significantly increased cell size was observed in infants with proven outflow obstruction.
- Most infants with vesicoureteral reflux showed normal cell size, but some had larger cells suggesting potential outflow impairment.
- Bladder specimens from newborns with triad syndrome and infants with giant bladders (rectovesical fistula, bowel dyskinesia) showed no muscle cell hypertrophy, suggesting non-obstructive, developmental origins.
- Bladder muscle cell hypertrophy reliably indicates outflow obstruction, even when mild.
Conclusions:
- Bladder smooth muscle cell hypertrophy is a reliable indicator of urinary tract outflow obstruction.
- Measurement of muscle cell size in surgical biopsies is a clinically useful method for diagnosing obstruction.
- Age-related changes in cell size should be considered in the assessment of bladder function.
Abstract:
This quantitative study has shown that the average size of the vesical smooth muscle cells of humans increases with age, whereas the average nuclear size remains constant. In the bladders of six babies with proven outflow obstruction, the cell size was signigicantly increased. In 23 of 25 bladders of infants and children with vesicoureteral reflux there was no apparent hypertrophy, but in two the cells were larger than normal and the micturition cystourethrograms exhibited features which may signify impairment of outflow. In two autopsy bladder specimens of two newborn, triad syndrome babies, there was no hypertrophy of muscle cells, indicating absence of obstruction in fetal life. Three giant bladders associated with rectovesical fistula deformities (two newborn specimens) and dyskinesia of the small and large bowel showed no hypertrophy of muscle cells, indicating that the enlargement was unlikely to be obstructive and appeared to be developmental in origin. Hypertrophy of muscle cells of the bladder indicated obstruction to the outflow, even when the degree of obstruction was mild. Muscle cell size can be measured on full thickness small surgical biopsy specimens prepared as paraffin sections and hence the method can be useful in clinical practice.