The Structural Basis for Congenital Valve Formation in the Posterior Urethra

Urethral valves

“…Lowsley [ 5] thought that valves were the result of anomalous junction of the ejaculatory (Wolffian) duct and the prostatic utricle (Müllerian duct): he described fibres attaching themselves around the entire circumference of the urethra in an autopsy specimen. Watson [ 6] deduced that valves represent the fusion of epithelium of the seminal coliculus with the roof of the urethra (the so‐called posterior urethral groove). Stephens [ 7] suggested that the type I valve results from an abnormal anterior insertion and persistence of the distal extremity of the Wolffian duct, whereas type III valves represent persistence of the urogenital membrane [ 7, 8].…”

Congenital urethral obstruction: Cobb's collar or prolapsed congenital obstructive posterior urethral membrane (COPUM)

“…The presence of a diverticulum above such an obstructing membrane.,and a prenatal diagnosis of hydronephrosis secondary to the obstruction, as seen in our third case, have not been previously reported. The bulbar urethral membrane probably represents a different embryological process to that of a COPUM, an obstruction which is possibly due to persistence of the attachment of the verumontanum to the anterior wall of the posterior urethra [18], whereas the bulbar urethral membrane is most likely to be due to partial persistence of the urogenital membrane [15].…”