Embryology and congenital abnormalities

Question 1

What is agenesis?

Answer 1

Absence of one or both kidneys

Question 2

What is a horseshoe kidney?

Answer 2

Fusion at either pole, usually lower

Question 3

What are the characteristics of infantile type polycystic kidneys?

Answer 3

Rare

Autosomal recessive

In perinatal group - causes terminal renal failure

Uniform bilateral renal enlargement

Question 4

What other congenital abnormality is polycystic kidney disease associated with?

Answer 4

Congenital hepatic fibrosis

Question 5

Which germ layer do the kidneys originate from?

Answer 5

Mesoderm

Question 6

How many mesonephric tubules are produced initially?

Answer 6

40

Question 7

At which time do the 40 mesonephric tubules regress to 20 pairs?

Answer 7

End of week 5

Question 8

What do the 20 pairs of mesonephric tubules differeniate into?

Answer 8

Excretory units

Question 9

When does the metanephros appear?

Answer 9

5 weeks

Question 10

When does the metanephros begin to function?

Answer 10

Weeks 9-11

Question 11

What does the metanephros become?

Answer 11

The permanent kidney

Question 12

What does the metanephros form from?

Answer 12

Ureteric bud

Metanephric blastema

Question 13

What happens at the metanephros at day 28?

Answer 13

Ureteric buds sprout from distal mesonephric ducts

Question 14

What forms from the uteretic bud?

Answer 14

Ureter

Renal Pelvis

Major calyces

Minor calyces

1-3 million Collecting Ducts

Question 15

What does the metanephric blastema become?

Answer 15

Nephron

Question 16

Where do the kidneys develop?

Answer 16

Pelvis

Question 17

At which stage of development are kidneys in their normal position?

Answer 17

Week 9

Question 18

What happens during weeks 5 and 6 during kidney ascent?

Answer 18

The mature kidneys lie in the pelvis with their hila pointed anteriorly

Question 19

How do the kidneys ascend from the pelvis?

Answer 19

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

Question 20

How do the kidneys come to be in a retroperitoneal position?

Answer 20

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

Question 21

Why might accessory renal arteries occur?

Answer 21

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

Question 22

How does a horseshoe kidney occur?

Answer 22

Inferior poles of metaneproi fuse before ascent

Kidney becomes trapped under IMA

Question 23

What develops from the hindgut endoderm?

Answer 23

Rectum

Primitive Urogenital Sinus

Question 24

What develops from the primitive urogenital sinus?

Answer 24

Bladder

Pelvic Urethra

Definitive Urogenital Sinus