Renal Embryology

Question 1

From what is the urinary system ultimately derived?

Answer 1

Intermediate mesoderm

Question 2

What are the 3 kidney systems in-utero?

Answer 2

1. Pronephros
2. Mesonephros
3. Metanephros

Question 3

By what point does the pronephros disappear?

Answer 3

End of the forth week

Question 4

In what in-utero kidney system do the Wolffian ducts lie?

Answer 4

Mesonephros

Question 5

What is the ureteric bud?

Answer 5

= an outgrowth of the caudal Wolffian duct

Question 6

From what is the definitive kidney formed?

Answer 6

Metanephros

Question 7

What should the allantois form as a mature structure?

Answer 7

Urachus, then median umbilical ligament

Question 8

What occurs when there is a failure of obliteration of the urachus?

Answer 8

Urachal fistula, the newborn persistently draining urine from the umbilicus

Question 9

What cause Potter sequence?

Answer 9

Malformation of the ureteric bud

Question 10

What occurs as a result of Potter sequence?

Answer 10

Bilateral renal agenesis. This results in foetus’ being unable to eliminate swallowed fluid into the amniotic cavity. This results in oligohyramnios. Consequently, the foetus cannot float and this results in limb and facial deformities due to compression of the foetus against the walls of the amniotic sac

Question 11

What are the 3 groups of deformities that can occur in Potter sequence?

Answer 11

1. Facial deformities - sloping forehead, flat nose etc.
2. Limb deformities - club foot, flipper hands etc.
3. Pulmonary hypoplasia

Question 12

What is the incidence of renal ectopy?

Answer 12

1 in 100

Question 13

How does renal ectopy present?

Answer 13

Obstructive hydronephrosis and vesicouteric reflux

Question 14

How does renal ectopy occur?

Answer 14

The kidneys must ascend during embryological development. To do this they must pass under the umbilical arteries. If they are unable to pass under the umbilical arteries, the kidneys will remain in the pelvis

Question 15

How do horseshoe kidneys occur?

Answer 15

While ascending from he pelvis, the kidneys may be pushed closer together. This can cause the lower poles to fuse, and they horseshoe kidney then become trapped under the inferior mesenteric artery

Question 16

In females, what should a finding of horseshoe kidneys prompt the work-up of?

Answer 16

Turner’s syndrome (7% with 45X0 have horseshoe kidneys)

Question 17

To what are individuals with horseshoe kidneys predisposed?

Answer 17

Kidney stone formation

Question 18

What is the medical term for kidney stone formation?

Answer 18

Nephrolithiasis

Question 19

What is VACTERL syndrome?

Answer 19

V = vertebral abnormalities
A = anal atresia/patency
C = cardiac defects
T = tracheal anomalies
E = esophageal anomalies
R =  renal anomalies
L = limb defects