Kidney development
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [1] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
Overview
In humans, the metanephros (adult kidney) begins as an aggregate of mesenchymal cells that are detectable by the fifth gestational week as two small areas in the intermediate mesoderm close to the pelvic aorta. It is approximately at this time that the nephric duct produces a finger-like projection called the ureteric bud that has, or will soon invade, the aggregate of cells known as the metanephric mesenchyme.
The ureteric bud of the nephric duct is stimulated by genetic signals emanating from the metanephric mesenchyme and the ureteric bud brings with it new genetic signals that will help the kidney form. The ureteric bud will grow into, and branch several times within, the metanephric mesenchyme, like a plant root penetrating and growing within ground soil.
Eventually, the ureteric bud will form the collecting ducts of the kidney and the ureters of the excretory system. The primitive nephric duct (pronephros) will degenerate to some degree but portions of it will go on to form the correct gender specific organs (gonads).
Once the ureteric bud has invaded the metanephric mesenchyme it will stimulate certain cells within the metanephric mesenchyme to condense around the tips of the branches of the ureteric bud and these cellular condensations will eventually form nephronic units (vascularized glomeruli).
In humans, all of the branches of the ureteric bud and the nephronic units have been formed by 32 to 36 weeks of gestation. However, these structures are not yet mature, and will continue to mature after birth. Once matured, humans have been estimated to possess approximately one million nephronic units (approximately 500,000 per kidney) or more.
After inducing the metanephric mesenchyme the lower portions of the nephric duct will migrate caudally (downward) and connect with the bladder, thereby forming the ureters. The ureters will carry urine from the kidneys to the bladder for excretion from the fetus into the amniotic sac. As the fetus develops, the torso elongates and the kidneys rotate and migrate upwards within the abdomen which causes the length of the ureters to increase.
External links
- Gray's s252
- University of Colorado
- Overview - Edinburgh
- University of Michigan
- University of Montreal: 3D animation male urogenital development
- University of Montreal: 3D animation female urogenital development
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
