Development of Urinary System Flashcards
What is the embryonic origin of the kidneys?
Intermediate mesoderm
What is the first part of the kidney to develop and in which region?
The pronephros Cervical region
What is in a nephrotome?
Glomerulus, Bowman’s capsule, proximal and distal convoluted tubule, collecting duct
What is the importance of the pronephros?
Produces a pronephric DUCT which extends from the cervical region to the cloaca Drives development of the next developmental stage
What is the cloaca?
Common chamber for the hindgut and urinary systems. Anterior - forms the urogenital sinus Posterior - forms the anus
What are the three key things that develop in urinary embryology?
Pronephros Mesonephros Metanephros
What happens during regression of the pronephric system?
Mesonephric tubules develop which will later form the Bowman’s capsule Capillaries develop which later form the glomerulus
What makes up a renal corpuscle?
Glomerulus and Bowman’s capsule
What is the urogenital ridge?
Area of intermediate mesoderm which gives rise to embryonic kidney and the gonad.
What induces the development of the definitive kidney?
The ureteric bud which sprouts from the mesonephric duct
What does the mesonephros do during development?
Performs renal function in the embryonic kidney
How does the collecting system develop?
Ureteric bud makes contact with the metanephric tissue so that it expands and branches to form the renal pelvis - splits into major and minor calyces
Where are the collecting system and excretory components derived from?
Collecting system - ureteric bud Excretory component - intermediate mesoderm under influence of ureteric bud
Where does the metanephric kidney appear?
In the caudal region
Describe the ascent of the metanephric kidney
In the pelvis, metanephros receives arterial supply from a pelvic branch of the aorta During its ascent, it is vascularised by arteries that come from the aorta at continuously higher levels. Lower vessels usually degenerate.
How does renal agenesis occur?
When the ureteric bud fails to interact with the intermediate mesoderm. Get failure of the kidney to form on that side.
What can abnormal location of the kidneys be caused by?
One of the kidneys fails to pass through the arterial fork formed by the umbilical arteries Kidneys stay in the pelvis close to commn iliac artery - pelvic kidney
How can horseshoe kidneys occur?
Pushed close together during passage through ascent so that the lower poles fuse. Stays at level of lumbar vertebrae since ascent prevented by inferior mesenteric artery.
What is Wilm’s tumour?
Cancer of kidneys Affects children by age 5 Due to a mutation Can be associated with other mortalities
What are duplication defects and ectopic ureteral orifices caused by?
Partial/complete splitting of the ureteric bud can cause ectopic ureteral opening/two ureters.
Where can ureters drain into in ectopic ureteral orifices?
Vagina, urethra, abnormal entrance in bladder, epididymal region
What causes cystic kidney disease?
Atresia of the ureter Urine cannot get to the bladder Large, fluid-filled cysts form in the kidney
What mode of inheritance is polycystic kidney disease?
Autosomal recessive
What happens in polycystic kidney disease?
Cysts form from collecting ducts so kidneys become large Renal failure occurs Presents early with a poor prognosis
What separates the urogential sinus and anal canal?
Urorectal septum
What connects the urogential sinus with the umbilicus?
The urachus
What does the urachus become when it loses its patency?
The median umbilical ligament
What is the outflow of the urinary tract during development?
Urogenital sinus, through the urachus, out of the umbilicus
What is the urogential sinus divided into?
Future bladder (largest upper part) Pelvic part (narrow canal) Phallic part Pelvic and phallic parts of the future urethra
What will the pelvic part of the urogenital sinus give rise to in males?
Prostatic and membranous parts of the urethra
Describe how in the male, the bladder, urethra and kidneys come together
Mesonephric ducts make contact with the urogenital sinus Ureteric bud sprouts from the mesonephric duct Smooth muscle appears and urogenital sinus begins to expand Ureteric buds and mesonephric ducts make independent openings in UGS Mesonephric ducts are maintained (ureters) and prostate and prostatic urethra are formed
Describe how in the female, the bladder, urethra and kidneys come together
Mesonephric ducts make contact with urogenital sinus Ureteric bud sprouts from mesonephric duct UGS expands and mesonephric ducts begin to regress Smooth musculature develops MD regression continues and ureteric bud opens into UGS
What do the mesonephric ducts become in men? What maintains them?
Ejaculatory ducts Androgen hormone
What is the female urethra formed from?
The pelvic part of the urogenital sinus
Where are the different parts of the male urethra formed from?
Pre-prostatic, prostatic and membranous formed from pelvic part of urogenital sinus Spongy part from the phallic part
What is a fistula?
Inappropriate connection between tracts
What is a urachal fistula?
When lumen of intraembryonic portion of the allantois persists. Can cause urine to drain into the umbilicus
What is exstrophy of the bladder?
A ventral body wall defect in which bladder mucosa is exposed so bladder opens onto abdominal wall.
What is hypospadias?
Defect in fusion of the urethral folds. Urethra opens onto the ventral surface rather than at the end of the glans
