Overview Kidney development progresses in a cranial to caudal direction intermediate mesoderm → urogenital ridge → nephrogenic cord → urinary system Pronephros non-functional appears by week 4 degenerates by week 5 Mesonephros development induced by pronephric duct forms mesonephric duct (Wolffian duct) interim kidney for 1st trimester opens into urogenital system and gives rise to male genital system Metanephros develops from mesonephric outgrowth called ureteric bud during week 5 fully canalized and functioning at week 10 nephrogenesis continues through 32 - 36 weeks of gestation derivatives include ureteric bud develops into ureter pelvises calyces and collecting ducts aberrant development may result in congenital malformations of the lower urinary tract metanephric mesenchyme interaction with ureteric bud causes metranephric mesenchyme to differentiate the renal structures from collecting tubules to glomerulus abnormal interaction with ureteric bud may cause malformations Ureteropelvic junction with kidney canalizes last most common site of obstruction in fetuswhich results inhydronephrosis Adult kidney embryo grows faster caudally causing a change in location of the kidney from S1 - S2 to a final position of T12 - L3 Developmental Abnormalities Renal agenesis failure of ureteric buds to form → no kidney formation Potter's Syndrome bilateral renal agenesis →oligohydramnios →fetal compression resulting in limb deformities clubbed feet facial deformities pulmonary hypoplasia Horseshoe kidney fusion of inferior poles ofkidneys ascension of kidney is prevented by the inferior mesenteric artery fused kidneys remain low in abdomen and may cause other renal vascular anomalies. normal kidney function