Renal- Anatomy and embriology

Question 1

Kidney embryology

• Pronephros
• Mesonephros
• Metanephros
• Ureteropelvic junction

Answer 1

week 4; then degenerates.

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

Permanent; first appears in 5th week of gestation; nephrogenesis continues through weeks 32–36 of gestation

last to canalize Ž most common site of obstruction (can be detected on prenatal ultrasound as hydronephrosis).

Question 2

Kidney embryology
ƒƒ Ureteric bud
ƒƒMetanephric mesenchyme (ie, metanephric blastema)

Answer 2

Derived from caudal end of mesonephric duct; gives rise to ureter, pelvises, calyces, collecting ducts; fully
canalized by 10th week

Ureteric bud interacts with this tissue; interaction induces differentiation and formation of glomerulus through to distal convoluted tubule (DCT)

*Aberrant interaction between these 2 tissues may result in several congenital malformations of the kidney (eg, renal agenesis, multicystic dysplastic kidney)

Question 3

Potter sequence (syndrome)
- clinical manifestations

Answer 3

POTTER sequence associated with:

Pulmonary hypoplasia
Oligohydramnios (trigger)
Twisted face
Twisted skin
Extremity defects
Renal failure (in utero)

Question 4

Potter sequence (syndrome)
- Etiology

Answer 4

Babies who can’t “Pee” in utero develop Potter
sequence

Causes include ARPKD, obstructive uropathy (eg, posterior urethral valves), bilateral renal agenesis, chronic placental insufficiency.

Question 5

Horseshoe kidney

Answer 5

Inferior poles of both kidneys fuse abnormally.

Associated with hydronephrosis (eg, ureteropelvic
junction obstruction), renal stones, infection, chromosomal aneuploidy syndromes (eg, Turner syndrome; trisomies 13, 18, 21), and rarely renal cancer.

Question 6

Congenital solitary functioning kidney

Answer 6

Born with only one functioning kidney. Majority asymptomatic with compensatory hypertrophy of contralateral kidney, but anomalies in contralateral kidney are common. Often diagnosed prenatally via ultrasound.

Question 7

Congenital solitary functioning kidney

- Unilateral renal agenesis

Answer 7

Ureteric bud fails to develop and induce differentiation of metanephric mesenchyme Ž complete absence of kidney and ureter.

Question 8

Congenital solitary functioning kidney

- Multicystic dysplastic kidney

Answer 8

Ureteric bud fails to induce differentiation of metanephric mesenchyme Ž nonfunctional kidney
consisting of cysts and connective tissue.

Predominantly nonhereditary and usually unilateral

Question 9

Duplex collecting system

Answer 9

Bifurcation of ureteric bud before it enters the metanephric blastema creates a Y-shaped bifid ureter.

Strongly associated with vesicoureteral reflux and/or
ureteral obstruction,  risk for UTIs.

Question 10

Posterior urethral valves

Answer 10

Membrane remnant in the posterior urethra in males; its persistence can lead to urethral obstruction.

Most common cause of bladder outlet obstruction in male infants.

Question 11

Renal blood flow

Answer 11

renal artery Ž segmental artery Ž interlobar artery Ž arcuate artery Ž interlobular artery Ž afferent arteriole
Ž glomerulus Ž efferent arteriole Ž vasa recta/ peritubular capillaries Ž venous outflow.

Question 12

Course of ureter

Answer 12

arises from renal pelvis,travels under gonadal arteries Ž over common iliac artery Ž under uterine artery/vas deferens (retroperitoneal).

Question 13

constrictions of ureter:

Answer 13

ƒƒ Ureteropelvic junction
ƒƒ Pelvic inlet
ƒƒ Ureterovesical junction