Session 2: Development of the Urinary System Flashcards
Embryological precursors to the kidneys.
Pronephros Mesonephros Metanephros In that order.
When does the pronephros develop?
Start of week 4 and will regress at the end of week 4.
When does the mesonephros develop?
End of week 4 and will regress at the end of week 8.
When does the metanephros develop?
At around week 5 and will not regress.
Functionality of the pronephros.
It has no function but it provides useful data on kidney development and it is a duct and structurally complete. The pronephric duct extends from cervical region to cloaca.
Functionality of the mesonephros.
It is functional but has no way of conserving water so it needs to develop further.
Functionality of the metanephros.
From end of first trimester the metanephros will be fully functional.
Subparts of the mesonephros.
Mesonephric tubules developing caudal to the pronephric region and mesonephric duct which becomes the mesonephros aka embryonic kidney.
What important role does the mesonephric duct have other than development of the male reproductive system?
It also sprouts the ureteric bud.
What is the ureteric bud?
The primoridum of the collecting system of the definitive kidney.
What does the collecting system of the kidneys develop from?
What about the excretory system?
Collecting system develops from the ureteric bud.
It will develop from the metanephric tissue cap from the metanephros aka the metanephric blastema under the influence of the ureteric bud.
The excretory system is the parenchyma aka the medulla and the cortex.
Which germ layer do the kidneys and the ureter arise from?
Intermediate mesoderm at the urogenital ridge.
Where do the kidneys develop?
In the pelvic region since that is where the urogenital ridge can be found.
Briefly explain the ascent of the kidneys from the pelvic region to the abdomen.
During the development of the kidneys they will ascend to the abdomen due to migration and expansion of the caudal region of the foetus.
The migration includes cranio-caudal shift from L4 to L1/T12.
Lateral displacement where the kidneys will meet up with the adrenal glands in their process.
A 90 degree rotation so the renal pelvis will face the midline.
What does the bladder derive from?
The hindgut aka the caudal portion of the primitive gut tube formed during embryonic folding in the fourth week of development.
Give examples of structural anomalies due to problems with migration.
Pelvic kidney where one of the kidneys don’t ascend properly.
Horseshoe kidney where the kidneys fuse.
Explain duplex kidney/ureter.
It can happen due to duplex ureteric buds leading to duplex kidneys and duplex ureters.
It can also be two ureters and one kidney.
This can be due to the splitting of the ureter.
It can be partial or complete. It is usually asymptomatic but can cause problems if there is an ectopic ureteral opening.
What is the ureteric bud?
Undifferentiated intermediate mesoderm that is caudal to the mesonephros.
What are the precursors of the kidneys?
The ureteric bud contacts the metanephric blastema and the bud will start to expand and branch.
The ureteric bud will be the renal pelvis and its major and minor calyx.
The metanephric blastema will be the parenchyma of the kidney (medulla and cortex).
The collecting system is derived from the ureteric bud, the excretory component is derived from intermediate mesoderm under the influence of the ureteric bud.
