Renal - Embryology

Question 1

What are the major embryological stages of kidney development? List them in order of development.

Answer 1

(1) Pronephros (2) Mesonephros (3) Metanephros

Question 2

At around what period in gestation is pronephros present? What is its fate?

Answer 2

Week 4; then degenerates

Question 3

What are the 2 major functions of the Mesonephros?

Answer 3

Functions as interim kidney for 1st trimester; Later contributes to male genital system

Question 4

What is the embryological name of the permanent kidney? When does it first appear in gestation?

Answer 4

Metanephros; First appears in 5th week of gestation

Question 5

Until what period of gestation does nephrogenesis occur?

Answer 5

Nephrogenesis continues through 32-36 weeks of gestation

Question 6

What are the 2 major parts of the metanephros? Briefly describe each in terms of general location/association.

Answer 6

(1) Ureteric bud - derived from caudal end of mesonephros (2) Metanephric mesenchyme - ureteric bud interacts with this tissue

Question 7

To what structures of the kidney does the ureteric bud give rise?

Answer 7

Ureter, pelvises, calyces, & collecting ducts

Question 8

To what structures of the kidney does the metanephric mesenchyme give rise, and how does this occur? What is an implication behind this?

Answer 8

Interaction of ureteric bud with this tissue induces differentiation and formation of glomerulus through to distal convoluted tubule; Aberrant interaction between these 2 tissues may result in several congenital malformations of the kidney

Question 9

What is the last structure to canalize in kidney development? Why is it clinically important?

Answer 9

Ureteropelvic junction; Most common site of obstruction (hydronephrosis) in fetus

Question 10

What are the causes of Potter’s syndrome?

Answer 10

Causes include ARPKD, posterior urethral valves, bilateral renal agenesis; Think: “babies who can’t ‘Pee’ in utero develop Potter’s

Question 11

What are the mechanisms/effects and consequent symptoms of Potter’s syndrome?

Answer 11

Oligohydramnios –> compression of fetus –> limb deformities, facial anomalies (low-set ears and retrognathia), and compression of chest –> pulmonary hypoplasia (cause of death)

Question 12

What is the deformity in a horseshoe kidney? What consequence does this deformity have?

Answer 12

Inferior poles of both kidneys fuse; As they ascend from pelvis during fetal development, horseshoe kidneys get trapped under inferior mesenteric artery and remain low in the abdomen

Question 13

How do horseshoe kidneys function?

Answer 13

Kidney functions normally

Question 14

With what disorder is horseshoe kidney associated?

Answer 14

Associated with Turner syndrome

Question 15

What is the underlying cause of multicystic dysplastic kidney? What are the consequences?

Answer 15

Due to abnormal interaction between ureteric bud and metanephric mesenchyme; This leads to a nonfunctional kidney consisting of cysts and connective tissue.

Question 16

What happens if multicystic dysplastic kidney is only unilateral? How common is this?

Answer 16

If unilateral (most common), generally asymptomatic with compensatory hypertrophy of contralateral kidney

Question 17

When and how is multicystic dysplastic kidney often diagnosed?

Answer 17

Often diagnosed prenatally via ultrasound

Question 18

What is the cause of death in Potter’s sequence (syndrome)?

Answer 18

Oligohydramnios –> compression of chest –> pulmonary hypoplasia (cause of death)

Question 19

What are 6 things to associate with Potter syndrome?

Answer 19

POTTER syndrome associated with: (1) Pulmonary hypoplasia (2) Oligohydramnios (trigger) (3) Twisted face (4) Twisted skin (5) Extremity defects (6) Renal failure (in utero).

Question 20

What are 4 conditions for which a horseshoe kidney increases the risk?

Answer 20

Increased risk for ureteropelvic junction obstruction, hydronephrosis, renal stones, & rarely, renal cancer (Wilms tumor).

Question 21

Draw a visual including and labeling the following: (1) Degenerated pronephros (2) Mesonephric duct (3) Mesonephros (4) Metanephros (5) Urogenital sinus.

Answer 21

See p. 522 in First Aid 2014 or p. 478 in First Aid 2013 for visual