Ureter

: 2. Kidney, 3. Renal pelvis, 4. Ureter, 5. Urinary bladder, 6. Urethra. (Left side with frontal section), 7. Adrenal glandVessels:8. Renal artery and vein, 9. Inferior vena cava, 10. Abdominal aorta, 11. Common iliac artery and veinWith transparency:''12. Liver, 13. Large intestine, 14. Pelvis The ureters are tubular structures, approximately in adults, The ureters are in diameter This location is also called the vesicoureteric junction. In the contracted bladder, they are about apart and about the same distance from the internal urethral orifice; in the distended bladder, these measurements may be increased to about . Development '' 1918 edition. The ureters develop from the ureteric buds, which are outpouchings from the mesonephric duct. This is a duct, derived from mesoderm, found in the early embryo. Over time, the buds elongate, moving into surrounding mesodermal tissue, dilate, and divide into left and right ureters. Eventually, successive divisions from these buds form not only the ureters, but also the pelvis, major and minor calyces, and collecting ducts of the kidneys. The mesonephric duct is connected with the cloaca, which over the course of development splits into a urogenital sinus and the anorectal canal. The urinary bladder forms from the urogenital sinus. Over time, as the bladder enlarges, it absorbs the surrounding parts of the primitive ureters. Finally, the entry points of the ureters into the bladder move upwards, owing to the upward migration of the kidneys in the developing embryo. ==Function==

The ureters are a component of the urinary system. Urine, produced by the kidneys, travels along the ureters to the bladder. It does this through regular contractions called peristalsis. File:Ultrasound_demonstration_of_ureteral_jet_effect_0301105703_1105300.gif|Ultrasound showing a jet of urine entering the bladder (large black section) through the ureter ==Clinical significance==

Ureteral stones A kidney stone can move from the kidney and become lodged inside the ureter, which can block the flow of urine, as well as cause a sharp cramp in the back, side, or lower abdomen. however a retrospective case study, which is a primary source, of where stones lodged based on medical imaging did not show many stones at the place where the iliac blood vessels cross. Most stones are compounds containing calcium such as calcium oxalate and calcium phosphate. The first recommended investigation is a CT scan of the abdomen because it can detect almost all stones. Management includes analgesia, often with nonsteroidal antiinflammatories. Reflux Vesicoureteral reflux refers to the reflux of fluid from the bladder into the ureters. This condition can be associated with urinary tract infections, particularly in children, and is present in up to 28–36% of children to some degree. as a result of narrowing within the ureter, or compression or fibrosis of structures around the ureter. Things outside the ureters such as constipation and retroperitoneal fibrosis can also compress them. A narrowed ureter may lead to ureteric enlargement () and cause swelling of the kidneys (hydronephrosis). If the cause cannot be removed, a nephrostomy may be required, which is the insertion of a tube connected to the renal pelvis which directly drains urine into a stoma bag. Cancer Cancer of the ureters is known as ureteral cancer. It is usually due to cancer of the urothelium, the cells that line the surface of the ureters. Urothelial cancer is more common after the age of 40, and more common in men than women; other risk factors include smoking and exposure to dyes such as aromatic amines and aldehydes. The ureter can be injured during surgery to nearby structures. usually near the suspensory ligament of the ovary or near the cardinal ligament, where the ureter runs close to the blood vessels of the uterus. Imaging Several forms of medical imaging are used to view the ureters and urinary tract. Ultrasound may be able to show evidence of blockage because of hydronephrosis of the kidneys and renal pelvis. Ureteroscopy is most commonly used for medium to large-sized stones when less invasive methods of removal cannot be used. ==Other animals==

All vertebrates have two kidneys located behind the abdomen that produce urine, and have a way of excreting it, so that waste products within the urine can be removed from the body. The structure specifically called the ureter is present in amniotes, meaning mammals, birds and reptiles. In monotremes, urine flows from the ureters into the cloaca. The ureters are ventral to the vasa deferentia in male placental mammals, but dorsal to the vasa deferentia in marsupials. In female marsupials, the ureters pass between the median and lateral vaginae. ==History==

The word "ureter" comes from the Ancient Greek noun , , meaning "urine", and the first use of the word is seen during the era of Hippocrates to refer to the urethra. The anatomical structure of the ureter was noted by 40 AD. However, the terms "ureter" and "urethra" were variably used to refer to each other thereafter for more than a millennium. The urinary tract including the ureters, as well as their function to drain urine from the kidneys, has been described by Galen in the second century AD. The first to examine the ureter through an internal approach, called ureteroscopy, rather than surgery was Hampton Young in 1929. More useful images were able to be produced when Edwin Hurry Fenwick in 1908 pioneered the use of tubes covered in material visible to X-rays inserted into the ureters, and in the early 20th century when contrasts were injected externally into the urinary tract (retrograde pyelograms). Unfortunately, much of the earlier retrograde pyelograms were complicated by significant damage to the kidneys as a result of contrast based on silver or sodium iodide. Hryntshalk in 1929 pioneered the development of the intravenous urogram, in which contrast is injected into a vein and highlights the kidney and, when excreted, the urinary tract. Things improved with the development by Moses Swick and Leopold Lichtwitz in the late 1920s of relatively nontoxic contrast media, with controversy surrounding publication as to who was the primary discoverer. Side-effects associated with imaging improved even more when Tosten Almen published a ground-breaking thesis in 1969 based on the less toxic low-osmolar contrast media, developed based on swimming experiences in lakes with different salinity. ==References==