Session 2: Development of the Urinary System Flashcards
(35 cards)
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.
What is the caudal portion of the hindgut which is a blind pouch?
The cloaca
What is the allantois?
A superoventral diverticulum of the hindgut which extends into the umbilical cord.
What happens to the lumen of the allantois?
It will regress and become the urachus.
What is the urachus?
The median umbilical ligament in adults.
What happens to the cloaca in urinary development?
The urorectal septum divides the urogenital sinus (future bladder and urethra) and the anorectal canal (future rectum and anal canal).
What does the superior part of the urogenital sinus do?
It is part of the allantois which will connect the umbilicus (median umbilical ligament).
What happens to the majority (middle) part of the urogenital sinus?
It will become the bladder
What happens to the lower part (also called the pelvic part) of the urogenital sinus in females?
It will develop into the urethra.
What is the pre-prostatic urethra, prostatic urethra, and membranous urethra derived from?
The narrowed lower segment of the urogenital sinus.
