The development of the male genitourinary system: II. The origin and formation of the urethral plate.

The origin, extent and topographical relationships of the urethral plate and its role in the pathogenesis of developmental anomalies (bladder extrophy, epispadias and hypospadias) remain incompletely resolved. The commonly held view that the urethral plate (the forerunner of the urethra) arises through distal proliferation of the cells of the anterior wall of the cloaca cannot explain these anomalies. Given this and its newfound implications for hypospadias repair the development of the urethral plate is presented in detail. New insights into the origin of associated congenital defects are revealed.