In females, the mesonephric duct regresses and the ureter alone remains. As the mesonephric duct and ureter are absorbed into the base of the bladder, they rotate so that the ureter meets the bladder cephalad to the point at which the mesonephric duct meets the urethra. This membrane then ruptures allowing passage of fetal urine into the urogenital sinus. At nine weeks of development the metanephros, which will become the mature kidney, starts to produce urine. As this fetal urine drains into the kidney, patency of the ureter is maintained.
Smooth muscle develops in the ureteric wall.
Later, this muscle will generate and propagate peristaltic contractions to conduct urine from the kidney to the bladder. Go to next page of Normal Development of the Ureter. See abnormal development of the ureter.