Ureteric duplication
Mark Davenport, James D. Geiger, Nigel J. Hall, Steven S. Rothenberg in Operative Pediatric Surgery, 2020
Two developmental structures give rise to the mature human kidney and ureters; the ureteric bud, which develops into the collecting system and ureters, and the metanephros, which develops into the nephrons and renal parenchyma. The ureteric bud begins as an epithelial outpouching off the distal mesonephric (Wolffian) duct. Typically, there is a single ureteric bud on each side giving rise to bilateral single ureters. The ureteric bud grows into the metanephros and a process of reciprocal induction causes nephrogenesis and ureteral branching. The renal unit with its branched collecting system migrates cranially, and the ureter grows caudally to merge with the urogenital sinus (the eventual bladder). Once incorporated into the urogenital sinus, the ureteral orifice migrates in a cranial and lateral direction from the bladder neck to its orthotopic position on the trigonal ridge.
Kidneys and ureters
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
The urinary tract is formed from the cloaca and intermediate mesoderm in parallel with the early differentiation of the metanephric blastema which will ultimately form the kidney. In the 6-week-old embryo, the mesonephric (Wolffian) duct and the paramesonephric (Mullerian) ducts run in parallel. By week 7, in the male, the Mullerian duct starts to regress, and the Wolffian duct will eventually develop into the epididymis and the caudal part of the vas deferens. In the female, the Mullerian ducts fuse to form the uterovaginal cord which will develop into the vagina. As the urogenital tract develops, there is simultaneous development of the fetal kidney. The ureteric bud arises from the distal end of the Wolffian duct as an unbranched diverticulum and invades the adjacent metanephric mesenchyme, initiating the branching collecting system within the primitive kidney. If the ureteric bud fails to develop, the kidney will not form. Renal development is controlled by the function of a number of transcription factors including PAX-2 and WT1.
SBA Answers and Explanations
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury in SBAs for the MRCS Part A, 2018
The definitive metanephroi are induced early in the fifth week by the ureteric buds that sprout from the mesonephric ducts. The ureteric bud induces the mesenchymal cells to condense around it, forming the metanephric blastema. The development of the ureteric bud and the metanephric blastema depends on reciprocal induction, neither being able to develop in the absence of the other. The metanephric blastema causes the ureteric bud to grow and bifurcate and the ureteric bud induces the mesenchyme to differentiate into nephrons. If the ureteric bud does not reach/signal properly to the surrounding mesenchyme, or vice versa, a kidney will not form (renal agenesis). If the ureteric bud bifurcates prematurely, a bifid ureter may result. Alternatively, if two ureteric buds develop an ectopic ureter may result.
Connection of ES Cell-derived Collecting Ducts and Ureter-like Structures to Host Kidneys in Culture
Published in Organogenesis, 2021
The connection of one ureteric bud derivative to another is not a feature of natural UB/collecting duct ureter development. The entire ureter and collecting duct system develop by branching morphogenesis from the UB, with no need for any connections to be made and with no evidence of connections ever being made. Indeed, the branches of the growing tree show mutual repulsion.12 Within the kidney, however, nephrons are required to make a connection between their distal pole and the collecting duct branch that induced their formation in the first place.16 It may be that the need to perform this connection, the mechanisms of which are still not understood in detail, means that UB-derived epithelia retain an innate ability to make connections that generate open-lumen communications between the tubules involved.
Clinical Presentations and Diagnostic Imaging of VACTERL Association
Published in Fetal and Pediatric Pathology, 2023
Gabriele Tonni, Çağla Koçak, Gianpaolo Grisolia, Giuseppe Rizzo, Edward Araujo Júnior, Heron Werner, Rodrigo Ruano, Waldo Sepulveda, Maria Paola Bonasoni, Mario Lituania
In VACTERL, anatomical anomalies must occur between the 23rd and 56th day post-conception, as this embryological window is critical for the development of the vertebrae (23-32 days), heart, tracheoesophageal structures, forearm bones (29-41 days), and anorectal region (45-56 days). Malsegmentation of the vertebrae is the result of timing abnormalities in the segmentation clock. Anorectal and tracheoesophageal defects are due to disturbed mesodermal proliferation and migration, epithelial-mesenchymal interactions, and apoptosis. Radial aplasia can be caused by impairment in laying down, condensing, or chondrifying the angle of the radius. Renal and urinary tract anomalies may be the result of failed growth of the ureteric bud, metanephric mesenchyme, and mesonephros/mesonephric duct. Cardiac defects involve altered cardiac septal development, as atrioventricular septal defects and tetralogy of Fallot defects are common [13].
Regenerating the kidney using human pluripotent stem cells and renal progenitors
Published in Expert Opinion on Biological Therapy, 2018
Francesca Becherucci, Benedetta Mazzinghi, Marco Allinovi, Maria Lucia Angelotti, Paola Romagnani
Important advances toward the generation of patient-specific organoids as tools for studying human kidney development, modeling disease, developing new drugs, and evaluating novel regenerative strategies derived from the development of efficient protocols for the differentiation of human pluripotent SCs into kidney organoids. Indeed, when induced to differentiate in renal epithelial cells, human pluripotent SCs spontaneously organize into structures resembling different segments of the nephron, from glomeruli to collecting ducts [6,42,60,61]. In particular, the exposure of iPSCs to different levels of Wnt agonist allowed authors to obtain pluripotent SCs of the metanephric mesenchyme and of the ureteric bud, giving rise to nephron structures that recapitulate the most important developmental steps of the embryonic kidney [60]. These structures showed functional properties such as a spatial and temporal pattern of expression of markers specific of different segments of the nephron [60]. Almost simultaneously, kidney organoids have been created from human ESCs [61]. Human pluripotent SC-derived organoids contain all the components of the fetal human kidney (nephrons, collecting ducts, endothelial cells, interstitium) [60,61].
Related Knowledge Centers
- Mesonephric Duct
- Development of The Urinary System
- Metanephrogenic Blastema