Embryology Flashcards
What are the two main functions of the kidney?
Filtration and collection
Where does the kidney proper begin to develop in the embryo?
Sacral part
What are the 4 parts of the mesoderm contained between the ecto and endoderm?
Paraxial
Intermediate
Somatic
Splanchnic
What part of the mesoderm will eventually give rise to the nephric structures?
Intermediate mesoderm
The aorta is in 2 parts during the initial development of the kidney. TRUE/FALSE?
TRUE
arteries extend from the developing kidneys to separate aortas, which eventually fuse together
Where does the process of segmentation of the intermediate mesoderm begin in the embryo?
At lower cervical spine region
The first part of the intermediate mesoderm to segment is known as what?
The pronephros (Greek for 1st kidney)
What section of intermediate mesoderm is next to segment after the pronephros?
The mesonephros
Why is the excretion of urine as an embryo important?
It contributes to development of amniotic fluid
As further segmentation occurs towards the kidney proper, what happens to the segementations at the level of the pronephros?
They regress
In males all of the pronephric and mesonephric tubes regress. TRUE/FALSE?
FALSE
all regress in females
In males, the mesonephric duct remains
The metanephros does NOT segment. TRUE/FALSE?
TRUE
it forms the metanephric blastema (aka the kidney proper)
When does the metanephros appear and when does it function between?
Appears at week 5
functions between weeks 9-11
How many pairs of mesonephric tubules are produced ?
40
On what day of development does the ureteric bud sprout and when does it penetrate the metanephric blastema?
Day 28 – ureteric buds sprout from distal mesonephric ducts
Day 32 – penetrate the Metanephric Blastema
What is the result of a ureteric bud which is too short and does not reach the metanephric blastema?
Kidney agenesis
Can an embryo survive with kidney agenesis?
Yes, but after birth it is not compatible with life.
Placenta did its work whilst baby was in the womb
What process creates the large spaces for collection during the branching of the renal pelvis?
Intussusception
What are the 4 parts of the nephron?
Bowman’s Capsule (Glomerulus)
Proximal Convoluted Tubule
Loop of Henle
Distal Convoluted Tubule
How do the nephrons establish a connection with the collecting ducts?
- Collecting tubule is associated with caps of metanephric tissue cells
- These arrange themselves into renal vesicles which eventually form the nephron alongside the collecting tubule
- The two fuse, creating a conduit between the nephron and collecting tubule
Where do the kidneys ascend to?
pelvis to L1 level
When do the kidneys begin to ascend?
during weeks 6-9
Before they ascend, where does the blood supply to the kidney come from?
common iliac arteries
Why are accessory arteries to the kidneys common?
New vessels are developing as they ascend and old vessels are meant to regress (sometimes they dont)
What is a pelvic kidney?
Anomaly where one kidney fails to ascend
Can still work from the pelvis
What is a horseshoe kidney and where does it normally sit?
Inferior poles of Metanephroi meet and fuse before ascent
⇒ kidney trapped beneath IMA
The cloaca (hindgut endoderm) gives rise to what 2 structures?
Rectum
Primitive Urogenital Sinus
The primitive urogenital sinus eventually forms what 3 structures?
Bladder
Pelvic urethra
Definitive Urogenital Sinus
What can potentially result from the cloaca forming both the rectum and primitive urogenital sinus?
Fistula between the two if it does not split properly
can also present as a vagino-anal fistula in females
What divides the cloaca into two?
Urorectal septum
What structure moves to connect the ureteric bud to the bladder directly?
Mesonephric duct
What does the mesonephric duct move downwards to become?
the early vas deferens in males
regresses after this in females
The trigone in the bladder is formed from the arrangement of the ureteric buds and mesonephric ducts. TRUE/FALSE?
TRUE
What is different about the trigone compared to the rest of the bladder wall?
It is non-contractile
What defects can occur if the bladder forms abnormally?
Urachal Fistula
Urachal Cyst
Urachal Sinus
