Editing Urinary tract (section)

=== '''Embryology''' ===

** Three separate excretory      organs appear in development, which succeed each other in time and space,      such that only the last is retained
*** Pronephros
**** Present only as clusters        of cells at the cranial part of the urogenital ridge
**** Only the duct persists,        which becomes known as the mesonephric (Wolffian) duct, which opens        caudally into the cloaca
*** Mesonephros
**** A ridge becomes visible,        the mesonephric ridge or mesonephros
**** Mesonephric tubules, the        first tubules, develop individually here and open into the mesonephric        duct
**** Some of these ducts        develop into genital structures such as epididymis
*** Metanephros (the true       precursor of the kidney)
**** Forms caudal to the        mesonephros as a mass of new tubules
**** This mass induces a bud,        the ureter, to grow from the caudal end of the mesonephric duct
**** Ureteric bud then        separates from the mesonephric duct, leaving it to form part of the        bladder and ductus deferens
**** Metanephros continues to        develop in the pelvis and is supplied by internal iliac artery. It        gradually migrates cranially, acquiring new blood supply from aorta.
**** At first, the hilum is        anterior, but the kidney rotates 90 degrees medially