Normal Human Kidney Development and Congenital Anomalies of the Kidneys and Urinary Tract

We present the sequence of events leading to the permanent human kidney. Nephrogenesis begins around 22 days after fertilisation and completes around the 34–36th week of gestation. There are three pairs of kidneys in human development: the pronephros, mesonephros and metanephros, arising sequentially from intermediate mesoderm on the dorsal body wall. The first two pairs involute and are resorbed during fetal life, but they are essential precursors to the metanephros and normal adult kidneys do not develop if they are disrupted. Human metanephric kidney development begins around day 28 post conception when the ureteric bud arises as an outpouching of the distal mesonephric duct/Wolffian duct. Glomeruli form from 8–9 weeks and nephrogenesis continues in the outer rim of the cortex until 34 weeks. Perturbation of early pathways can lead to a range of phenotypes including renal agenesis, dysplasia and duplex kidneys, as well as malpositioning defects such as pelvic or horseshoe kidneys if they fail to ascend to their normal 12th thoracic to 3rd lumbar vertebral site during development.