Curriculum Module
Urogenital System Development
The urinary and reproductive systems share the intermediate mesoderm as their common origin. The kidney passes through three overlapping stages, while sexual differentiation is driven by the SRY gene and hormonal signaling on the bipotential gonad.
Shared Embryonic Origin
Both systems derive from Intermediate Mesoderm, which condenses into the Urogenital Ridge. The inner Nephrogenic Cord runs the length of the embryo's back as the foundation for kidney formation.
Both systems drain into a shared cavity—the Cloaca. Between weeks 4–7, the Urorectal Septum grows downward, dividing the cloaca. Its tip forms the perineal body.
The Allantois lumen obliterates to form the Urachus (median umbilical ligament). The Urogenital Sinus divides into the bladder (proximal), urethra (middle/distal), and external genitalia primordium (phallic).
Key Insight
This stage is critical for the formation of embryonic support structures, establishing the main body axis.