Renal Embryology Flashcards
(20 cards)
When does the pronephros degenerate?
Week 4
What is the first functional unit of the fetal kidney?
Mesonephros (functions as interim kidney for 1st trimester)
What adult structure does the mesonephros later contribute to?
Male genital system (vas deferens)
What is the final embryologic kidney structure and how long does nephrogenesis continue?
Metanephros (permanent) –> first appears at 5 weeks gestation
Nephrogenesis continues through 32-36 weeks gestation
What two structures grow laterally to form the metanephros?
- Ureteric Bud
2. Metanephric Duct
What is the ureteric bud derived from and what adult structures does it give rise to?
Derived from the caudal end of mesonephric duct
Gives rise to: ureter, pelvises, calyces, collecting ducts
Fully canalized by 10th week
What is the significance of the metanephric mesenchyme and what adult structures does it give rise to?
Ureteric bud interacts with this tissue; interaction induces differentiation and formation of glomerulus through to the distal convoluted tubule (DCT)
What is the last site to canalize in the fetal kidney?
Ureteropelvic junction
Most common site of obstruction (hydronephros) in fetus
What is the Potter Sequence (syndrome)?
Oligohydraminos (too little amniotic fluid) –> compression of developing fetus –> limb deformities, facial anomalies (eg. low set ears and retrognathia, which is an abnormal posterior positioning of the mandible), compression of the chest and lack of amniotic fluid aspiration into fetal lungs –> pulmonary hypoplasia (cause of death)
Think: “Babies who can’t PEE in utero develop POTTER”
Pulmonary hypoplasia Oligohydraminos Twisted face Twisted skin Extremity Defects Renal failure (in utero)
What are common causes of the Potter Sequence (syndrome)?
- ARPKD (autosomal recessive polycystic kidney disease)
- obstructive uropathy (eg. posterior urethral valves)
- bilateral renal agenesis
What is a horseshoe kidney?
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
Kidneys function normally
What are common associations with horseshoe kidney?
- Ureteopelvic junction obstruction
- Hydronephros
- Renal Stones
- Infection
- Chromosomal aneuploidy syndromes (especially TURNERS, but also Edwards, Down, Patau)
- Rarely renal cancer
What is multicystic dysplastic kidney?
Due to abnormal interaction between ureteric bud and metanephric mesenchyme –> leads to a nonfunctional kidney consisting of cysts and connective tissue
If unilateral (most common), usually as symptomatic with compensatory hypertrophy of contralateral kidney
Usually diagnosed prenatally with ultrasound
What is a duplex collecting system?
Bifurcation of the ureteric bud before it enters metanephric blastema creates Y-shaped bifid ureter.
Can alternatively occur when two ureteric buds reach and interact with the metanephric blastema
Strongly associated with vesicoureteral reflux and/or ureteral obstruction (increased risk of UTIs)
Which kidney is taken during a donor transplantation and why?
Left kidney because it has a longer renal vein
What direction does blood flow from afferent and efferent arterioles with respect to the glomerulus?
Afferent = Arriving Efferent = Exiting
Which cells in the kidney release Renin?
Juxtaglomerular Cells release renin when:
- Decrease in Na levels
- Decrease in BP
- Increase in sympathetic tone
What are the branches of the arteries that supply the kidney?
Think: “Real Sports Lovers Interests Are Intertwining Always”
Renal Segmental Lobar Interlobar Arcuate Interlobular Afferent
What arteries supply the upper 1/3, middle 1/3 and lower 1/3 of the ureters?
upper 1/3: renal arteries
middle 1/3: common iliac and gonadal arteries
lower 1/3: branches of internal iliac arteries
What is the relationship between the ureter and the gonadal arteries?
Think: “Water Under the Bridge”
Ureters pass under the uterine artery and vas deferens
Gynecologic procedures involving ligation of uterine vessels traveling in cardinal ligament may damage the ureter –> ureter obstruction or leak
