Embryology and congenital abnormalities Flashcards
What is agenesis?
Absence of one or both kidneys
What is a horseshoe kidney?
Fusion at either pole, usually lower
What are the characteristics of infantile type polycystic kidneys?
Rare
Autosomal recessive
In perinatal group - causes terminal renal failure
Uniform bilateral renal enlargement
What other congenital abnormality is polycystic kidney disease associated with?
Congenital hepatic fibrosis
Which germ layer do the kidneys originate from?
Mesoderm
How many mesonephric tubules are produced initially?
40
At which time do the 40 mesonephric tubules regress to 20 pairs?
End of week 5
What do the 20 pairs of mesonephric tubules differeniate into?
Excretory units
When does the metanephros appear?
5 weeks
When does the metanephros begin to function?
Weeks 9-11
What does the metanephros become?
The permanent kidney
What does the metanephros form from?
Ureteric bud
Metanephric blastema
What happens at the metanephros at day 28?
Ureteric buds sprout from distal mesonephric ducts
What forms from the uteretic bud?
Ureter
Renal Pelvis
Major calyces
Minor calyces
1-3 million Collecting Ducts
What does the metanephric blastema become?
Nephron
Where do the kidneys develop?
Pelvis
At which stage of development are kidneys in their normal position?
Week 9
What happens during weeks 5 and 6 during kidney ascent?
The mature kidneys lie in the pelvis with their hila pointed anteriorly
How do the kidneys ascend from the pelvis?
As the pelvis and abdomen grow the kidneys slowly move upward
By the 7th week the hilum points medially and kidneys are located in abdomen
How do the kidneys come to be in a retroperitoneal position?
Initially kidneys will ascend as abdomen grows
As the embryo continues to develop in a caudal direction, the kidneys are left behind and eventually come to lie in a retroperitoneal position at the level of L1 by the 9th week development
Why might accessory renal arteries occur?
As kidneys ascend in the abdomen, they take blood supply from branches of the aorta closest to them
These usually degenerate, but may remain in place
How does a horseshoe kidney occur?
Inferior poles of metaneproi fuse before ascent
Kidney becomes trapped under IMA
What develops from the hindgut endoderm?
Rectum
Primitive Urogenital Sinus
What develops from the primitive urogenital sinus?
Bladder
Pelvic Urethra
Definitive Urogenital Sinus
