Ureteropelvic junction

The ureteropelvic junction (UPJ, also uretero-pelvic junction or ureteral pelvic junction) is the junction between the ureter and the renal pelvis of the kidney.

During the embryologic development of the kidney, this is the last part of the ureter to become patent.

Failure of this segment of ureter to become patent during development is the most frequent cause of bilateral hydronephrosis, particularly in male neonates. Pyeloplasty, which involves excision of the stenotic section and creation of a new junction, is the most common and effective treatment for this problem.

Anatomy of the urinary system

Abdomen

Kidneys

Layers	Fascia Capsule Cortex column Medulla sinus pyramids medullary interstitium Lobe Cortical lobule Medullary ray Nephron

Intrarenal arteries	Renal artery Segmental arteries Interlobar arteries Arcuate arteries Interlobular arteries Afferent arterioles

Renal tubule	Renal corpuscle Glomerulus Bowman's capsule Proximal convoluted tubule Loop of Henle Descending Thin ascending Thick ascending Distal convoluted tubule Connecting tubule Collecting ducts Renal papilla Minor calyx Major calyx Renal pelvis

Intrarenal veins	Efferent arterioles Peritubular capillaries/Vasa recta Arcuate vein Interlobar veins Renal vein

JGA	Macula densa Juxtaglomerular cells Mesangium Extraglomerular mesangial cell

Filtration	Glomerular basement membrane Podocyte Filtration slits Mesangium Intraglomerular mesangial cell Tubular fluid

Ureters

Pelvis

Bladder	Apex Uvula Neck Median umbilical ligament Muscular layer Trigone Detrusor Mucosa Submucosa

Urethra	Urethral sphincters External sphincter muscle of male urethra External sphincter muscle of female urethra Internal sphincter muscle of urethra

Index of the urinary system

Description	Anatomy Physiology Development Cells

Disease	Electrolyte and acid-base Congenital Neoplasms and cancer Other Symptoms and signs eponymous Urine tests findings Blood tests

Treatment	Procedures Drugs potassium and phosphate Intravenous fluids