Pathogenesis of the prune belly syndrome.

The triad of abnormalities of the prune belly syndrome may arise simply from the effects of early urethral obstruction or alternatively from a basic defect of the mesoderm from which the triad of abnormalities develops. The urethra and genital tract of 21 prune belly syndrome specimens and 23 specimens of Young's posterior urethral valves types 1 and 3 were compared in a study for differences in the pathological anatomy that may elucidate the controversy. The specimens were dissected and investigated radiographically and histologically. The seminal ducts and vesicles, and prostatic glands were abnormal in the prune belly syndrome specimens and normally developed in the posterior urethral valve specimens. We contest that this major difference stems from a primary defect of the intermediate and lateral plate mesoderm in the prune belly syndrome which would affect the embryogenesis not only of the mesonephric and paramesonephric ducts but also of the musculature of the abdominal wall and urinary organs, and that prune belly valves when present are intrinsic components of the mesodermal defect of the prune belly syndrome urethra.