Development of the urinary system Flashcards
What germ layer contributes to the development of the kidney?
Mesoderm
What part of the mesoderm contributes to the development of the kidney?
Intermediate mesoderm
What part of the intermediate mesoderm contributes to the development of the kidney?
Urogenital ridge
How many kidney systems form during the development of the urinary system?
Three
What are the different kidney systems that form during the development of the urinary system?
Pronephros
Mesonephros
Metanephros
Where in the foetus does the pronephros appear?
In the cervical region
What is the function of the pronephros?
Has no function itself
What is the purpose of the development of the pronephros?
To produce the pronephric duct
Where does the pronephric duct extend from and to?
Cervical region
to the cloaca
What is the function of the pronephric duct?
Drives the development of the mesonephros
Where in the foetus does the mesonephros appear?
Caudal to the pronephros
How does the mesonephros develop?
Mesonephric tubules form
together with the mesonephric duct make up the mesonephros
What is the function of the mesonephros?
Produces urine
What drains the urine from the mesonephros?
Mesonephric duct
What does the mesonephric duct drain urine into?
Urogenital sinus
What are the other functions of the mesonephric duct, aside from draining urine from the mesonephros?
Ureteric bud sprouts from the mesonephric duct
Role in development of male reproductive system
Where in the foetus does the ureteric bud appear?
Caudal to the mesonephros
What is the function of the ureteric bud?
Grows and branches
Comes into contact with metanephric blastema
Stimulates the metanephric blastema to differentiate into the metanephros
Where is the metanephric blastema located?
Caudal to the mesonephros
What is metanephric blastema made up of?
Undifferentiated intermediate mesoderm
What part of the metanephros does the ureteric bud form?
Collecting system
- minor calyces
- major calyces
- renal pelvis
- ureter
What part of the metanephros does the metanephric blastema form?
Excretory system
-nephrons
Where in the foetus does the metanephros appear?
Pelvic area
Where does the metanephros migrate to in the foetus?
Posterior abdominal area
How does the metanephros migrate from the pelvic area to the posterior abdominal area?
This is mostly due to the lengthening of the trunk of the foetus
partly due to true movement of metanephros in caudal to cranial direction
What does the metanephros cross over during its migration from the pelvic area to the posterior abdominal area?
Umbilical artery
How does the blood supply of the metanephros change as it migrates from the pelvic area to the posterior abdominal area?
Recieves new arterial branches from the aorta as it moves upwards
What happens to the old arterial branches from the aorta that supplied the metanephros?
Disappear
occasionally remain
What are accessory renal arteries?
Remnants of the old arterial branches from the aorta that supplied the metanephros
What is the significance of the blood supply of acessory renal arteries to the kidneys?
They are end arteries
meaning they are the only blood supply to that region of tissue
What are some developmental defects caused by abnormal migration of the metanephros?
Pelvic kidney
Horseshoe kidney
What is a pelvic kidney?
Kidney located in the pelvis instead of the posterior abdominal area
What is the cause of a pelvic kidney?
Metanephros failed to migrate upwards
because it got caught on the umbilical artery
What is a horseshoe kidney?
Inferior poles of kidneys are fused
fused part is caught under the inferior mesenteric arteries
What is the cause of a horseshoe kidney?
Both metanephros move towards the midline to avoid the umbilical arteries during their migration upwards
move too close to each other and fuse at their inferior poles
fused part gets caught under inferior mesenteric artery during their migration upwards
What is renal agenesis?
Kidney failed to develop
What is the cause of renal agenesis?
Ureteric bud fails to successfully interact with metanephric blastema
What can splitting of the ureteric bud lead to?
Duplication of a ureter
Duplication of parts of kidney, or whole kidney
What can duplication of a ureter lead to?
Ectopic ureteral orifice
What is an ectopic ureteral orifice?
Ureter opens up into an abnormal site, not the urinary bladder as normal
What is the main symptom of an ectopic ureteral orifice? Why?
Urinary incontinence
because the sphincters do not control the passage of urine through it
What is the first opening of the urinary tract? What drains into this?
Cloaca
the pronephric duct
What is the second opening of the urinary tract? What drains into this?
Urogenital sinus
the mesonephric duct
How is the urogenital sinus formed?
Urorectal septum divides the cloaca into two compartments
the urogenital sinus is the anterior compartment
What happens to the urachus?
Closes up
What is the remnant of the urachus?
Median umbilical ligament
What does the urogenital sinus develop into?
Superior part develops into the urinary bladder
Inferior part develops into the urethra
What does the ureter drain into during development?
Initially it drains into the urogenital sinus
But as the urinary bladder develops, it drains into the urinary bladder
How does the female urethra develop?
From the inferior part of the urogenital sinus
How does the male urethra develop?
The mesonephric ducts run through the bladder and prostate gland
forming the prostatic urethra
The opening of the urogenital sinus is surrounded by genital folds
which fuse together to form the spongey urethra
What is hypospadias?
Urethra opens at the ventral surface of the penis
rather than at the tip of the head of the penis
What is the cause of hypospadias?
Defect in fusion of genital folds
What part of the kidney do accessory renal arteries supply?
Inferior part of kidney
