Embryology of the Renal System

Question 1

What are the 3 germ layers of the embryo?

Answer 1

Ectoderm
Mesoderm
Endoderm

Question 2

What of the 3 germ layers does the kidneys form from?

Answer 2

Mesoderm

Question 3

What are the 3 parts of the mesoderm?

Answer 3

Paraxial
Intermediate
Lateral

Question 4

What part of the mesoderm does the kidneys form from?

Answer 4

Intermediate mesoderm

Question 5

What does the dorsal aorta form?

Answer 5

Descending aorta

Question 6

What are the 3 stages of kidney development in the embryo?

Answer 6

Pronephros
Mesonephros
Metanephros

Question 7

At what end of the embryo does the intermediate mesoderm begin to segment?
What does this form?
When about does this occur?

Answer 7

Cranial end
Pronephri
Day 22

Question 8

Are pronephri functional?

Answer 8

No

Question 9

What do the pronephri become?

Answer 9

Mesonephros

Question 10

Where does the filtrate from mesonephros drain to?

Answer 10

Mesonephric duct which is forming alongside the mesonephri

Question 11

Are mesonephri functional?

Answer 11

Yes

Question 12

How many mesoneprhic tubules are originally formed?
How many are left once these have regressed?
What happens to the remaining mesonephric tubules?

Answer 12

40
20
Function as excretory units between weeks 6-10 and then regress

Question 13

When do the mesonephric tubules begin to regress?

Answer 13

End of week 5

Question 14

What vertebral levels are the remaining mesonephric tubules left at?

Answer 14

L1-L3

Question 15

What develops at approximately week 5?

Answer 15

Metanephros

Question 16

When does the metanephros begin to function?

Answer 16

Weeks 9-11 (mesonephros stops functioning at about week 10)

Question 17

What does the metanephros develop into?

Answer 17

The permanent kidney

Question 18

What does the metanephros develop from?

Answer 18

Ureteric bud (collecting system)
Metanephric blastema (filtering system)

Question 19

What does the ureteric buds sprout from?

Answer 19

The mesonephric ducts

Question 20

At what day does the ureteric buds sprout from the distal mesonephric ducts?

Answer 20

Day 28

Question 21

At what day does the ureteric buds penetrate a portion of the metanephric mesenchyme?

Answer 21

Day 32

Question 22

What does the metanephric mesenchyme become once the ureteric bud connects to it?

Answer 22

Metanephric blastema

Question 23

What is the outcome of failure of the metanephric mesenchyme and ureteric bud to connect (either due to failure of ureteric bud to grow fully or failure of it to grow at all)?

Answer 23

Kidney agenesis (bilateral kidney agenesis is incompatible with life)

Question 24

What part of the adult kidney does the ureteric bud form?

Answer 24

the collecting system e.g. ureter, renal pelvis, major/ minor calyces, 1-3 million collecting ducts

Question 25

How does major calyxs form?

Answer 25

Metanephric mesenchyme signals to the ureteric bud to start diving (get approximately 4 generations of bifurcation) Intussusception then occurs leading to the major calyx This repeated to form the minor calyxs, etc.

Question 26

What part of the metanephros forms the nephron?

Answer 26

Metanephric blastema

Question 27

How does the nephrons of the kidney form?

Answer 27

Branches of the ureteric buds release signals causing metanephric tissue to form nephric vesicles These elongate and eventually join with the ureteric bud = collecting tube with nephron attached (also seek out capillaries and expand around them = Bowman's capsule)

Question 28

What forms the collecting ducts?

Answer 28

Ureteric bud

Question 29

Where in the body is the kidney formed? | What happens to them once they have formed?

Answer 29

Very low down in the pelvis | Migrate up

Question 30

How do the renal arteries develop?

Answer 30

Start very low down on the aorta and then as the kidneys migrate up, new vessels form and old ones regress (if they don't regress, accessory renal artery is formed)

Question 31

Are the adrenal glands related to the kidney developmentally/

Answer 31

No

Question 32

At what week of development are the kidneys lying in the correct position?

Answer 32

Week 9

Question 33

What developmental anomaly occurs when the inferior poles of metanephroi meet and fuse before ascent?

Answer 33

Horseshoe kidney

Question 34

Why is a horseshoe kidney located lower down in the pelvis?

Answer 34

It is trapped beneath inferior mesenteric artery which projects from the anterior rota

Question 35

What germ layer does the bladder form from?

Answer 35

Endoderm

Question 36

What does the bladder form from?

Answer 36

The primitive urogenital sinus which forms from the cloaca (hindgut endoderm

Question 37

What are the 2 structures that the cloaca (hindgut endoderm) forms?

Answer 37

Rectum | Primitve urogenital sinus

Question 38

What structures does the primitive urogenital sinus form? (3)

Answer 38

Bladder Pelvic urethra Definitive urogenital sinus

Question 39

Where does the cloaca pass into in development?

Answer 39

Umbilical cord

Question 40

Out of the ureteric bud and the mesonephric duct, what initially communicates with the bladder?

Answer 40

Mesonephric duct

Question 41

What does the mesonephric contribute to in males?

Answer 41

Reproductive tract

Question 42

What tissue forms the trigone in the bladder?

Answer 42

Tissue of the mesonephric duct where it comes together (non-contractile unlike the rest of the bladder)

Question 43

Name for when the communication between the bladder and anterior abdominal wall is retained?

Answer 43

Urachal fistula

Question 44

What is formed when there is a persistent portion of urachus between the umbilicus and bladder?

Answer 44

Urachal cyst

Question 45

What forms when there is a non-communicating dilation of the arches at the umbilical end?

Answer 45

Urachal sinus