15: Renal Embryology

Question 1

Where is intermediate mesoderm located?

Answer 1

Immediately lateral to each somite

Question 2

Ascent of the kidneys

Answer 2

Kidneys lie within pelvis, and gradually “ascend” into pelvis - dont actually move, but embryo lengthens

Question 3

When are kidneys in adult positioning by?

Answer 3

9th week

Question 4

Initial vs definitive blood supply to kidneys

Answer 4

Initial: from common iliacs
Definitive: abdominal aorta

Question 5

Issues with having accessory renal vessels

Answer 5

Can obstruct ureter and lead to hydronephrosis

Question 6

Which is more common, accessory renal arteries or veins?

Answer 6

Arteries (found in 25% of adults)

Question 7

Structures formed from the ureteric bud vs metanephrines blastema

Answer 7

Ureteric bud -> ureter, renal pelvis, calyces, CDs

Metanephrines blastema -> Bowman’s capsule, prox tubule -> distal tubule

Question 8

unilateral renal agenesis S/S and when to suspect it

Answer 8

Typically asymptomatic, suspected in infants with 1 umbilical artery

Question 9

Bilateral renal agenesis

Answer 9

Results in oligohydramnios and is non-viable due to pulmonary hypoplasia

Question 10

Incomplete and complete divisions in ureter duplications

Answer 10

Incomplete division -> divided kidney and bifid ureter

Complete division -> double kidney and bifid ureter or separate ureters

Question 11

How does horseshoe kidney form?

Answer 11

Fusion of inferior poles to form isthmus between kidneys

Question 12

Symptoms of horseshoe kidney

Answer 12

Typically asymptomatic but can be problematic in conditions like pregnancy

Question 13

Why is the horseshoe kidney more inferiorly positioned?

Answer 13

Ascent is prevented by IMA

Question 14

ARPKD: autosomal recessive polycystic kidney disease presentation

Answer 14

S/S present before/shortly after birth, cysts present in both kidneys, renal insufficiency, 25% associated with pulmonary hypoplasia

Question 15

Multicystic dysplastic kidney disease

Answer 15

Multiple non-communicating cysts of varying size on the kidney, likely due to dilations of the loop of Henle

Question 16

What does the vesical part of the urogenital sinus form?

Answer 16

Urinary bladder

Question 17

What forms bladder epithelium?

Answer 17

Endoderm

Question 18

What forms bladder submucosa and muscularis?

Answer 18

Splanchnic mesoderm

Question 19

What forms the bladder trigone area?

Answer 19

Intermediate mesoderm

Question 20

What 2 things does the allantois form in the bladder?

Answer 20

Urachus, median umbilical ligament

Question 21

Exstrophy of the bladder

Answer 21

Defective closure of ventral abdominal wall -> exposure of mucosa of the posterior wall of the bladder

Question 22

When does exstrophy of the bladder occur?

Answer 22

During body folding, 4th week

Question 23

Urachal cyst

Answer 23

Remnants of epithelial lining of urachus that can become infected and enlarged

Question 24

Urachal sinus

Answer 24

End of the urachus remains open into the bladder or umbilicus

Question 25

Urachal fistula

Answer 25

Entire urachus remains patent and allows urine to escape from umbilical orifice

Question 26

Three urachal anomalies

Answer 26

Urachal cysts, urachal sinus, urachal fistula