Kidney Development - Bolender Flashcards
The entirety of the kidney develops from what precursor tissue?
Where it it located in the developing embryo (~Day 18-20)
Intermediate mesoderm.
Located lateral to the paraxial mesoderm.
What is the name of the structure from which the kidney and gonads both develop?
Both develop from the nephrogenic cord; the kidneys from the metanephron, the gonads from the mesonephron.
What are the two components of the mesonephric kidney?
Which of these two structures acts as a source of signaling?
Where is it located?
The mesonephric duct and tubules.
The duct is a source of inductive signaling.
The mesonephric kidneys are located bilaterally in the thoracolumbar region.
What is the cloaca?
How do the mesonephron and metanephron communicate with this structure?
A primitive outflow region for both the GU and GI tracts in the developing embryo.
Both drain to it, via the nephrogenic cord or a structure common to it and the metanephric diverticulum.
What is the function of the mesonephric tubules?
How do they develop?
Mesonephric tubules are immature nephrons, which serve renal function briefly until the mature kidneys form.
Develop via signals derived from the mesonephric duct, differentiating cranial to caudal.
What are the two components of the metanephric kidneys?
Can you recall what each one will ultimately give rise to?
Metanephric Diverticulum: Epithelial tissue which will form the bulk of the urinary collection system.
Metanephric Mesenchyme: Gives rise to tubular, vascular, and presumably interstitial tissue of the kidneys.
Describe the reciprocal interactions that occur between the metanephric diverticulum and mesenchyme.
The mesenchyme signals for formation & growth of the diverticulum into branches (GDNF).
Signals from the diverticulum prevent apoptosis of mesenchyme, and promote its differentiation and aggregation around the diverticulum.
Explain the pathophysiology and clinical findings in Oligohydramnios.
In oligohydramnios, a deficit of amniotic fluid results in pulmonary hypoplasia, growth deficiency, and fetal compression (Potter’s facies, limb defects).
Distinguish between Potter’s syndrome and Oligohydramnios.
Historically, Potter’s syndrome referred to the clinical syndrome seen in babies with oligohydramnios caused by renal agenesis. It is often used interchangeably with oligohydramnios, however.
What are some possible causes of Potter’s syndrome?
Bilateral renal agenesis
Polycystic kidney diseases
Severe urinary tract obstruction
Chronic amniotic leak
What conditions are associated with polyhydramnios?
Diabetes, multiple gestation, ancencephaly, esophageal atresia.
Describe how nephrons form.
What is the S-shaped tubule missing?
Signals from the tips of the metanephric diverticulum (Ampullae) cause the mesenchyme to aggregate and form an epithelial vesicle; the tubule forms from collecting duct backwards to the glomerulus.
S-shaped tubule is not vascularized.
What ultimately forms from the proximal, middle, and distal parts of the S-shaped nephron?
Proximal: Distal tubule & loop of henle
Middle: Proximal tubule
Distal: Renal corpuscle
What signals for migration of vascular tissue to the nephrons?
VEGF.
What is on the DDx for a neonatal unilateral flank mass?
What if it is a bilateral flank mass?
Unilateral: Hydronephrosis, Cystic kidney diseases, Renal tumors.
Bilateral: Most likely PCKD, but some other bilateral conditions are possible (eg Bilateral dysplastic kidney)
Multicystic Dysplastic Kidney
Describe its etiology.
What is found on biopsy?
How is renal function affected?
Multicystic Dysplastic Kidney
Congenital malformation of parenchyma, but not inherited.
Cysts, primitive ductules and cartilage.
Since the contralateral kidney hypertrophies, function is generally preserved.
Multicystic Kidney Disease
What are some possible complications?
How is it treated?
Multicystic Kidney Disease
Hypertension. Reflux of the contralateral kidney.
Not treated at all unless failure is severe, then nephrectomy.
How many generations of diverticular branches are there?
Distinguish between them.
Usually about 15 generations.
Early generations grow little. 3rd-6th form calyces/pelvis/ureter. Polar branches grow faster; distal to 5th & 6th form collecting ducts.
T/F: The fetal kidney must be bisected to visualize lobes.
False; Renal lobes are visible externally.
Summarize a few possible forms of renal developmental defect.
Hypoplasia, dysplasia, duplication (ureter/kidney), fusion (horseshoe kidney), ectopic kidney.
What hereditary conditions cause congenital kidney dysfunction?
Usually polycystic kidney diseases. Medullary cystic disease is also inherited (autDom)
What is a Wilm’s Tumor?
What mutation is it associated with?
A blastema containing many different tissue types, seen commonly in children.
Associated with WT1 mutation on chromosome 11
Ureteropelvic Junction Obstruction
Distinguish between the adult and infant presentations.
How is it diagnosed?
Ureteropelvic Junction Obstruction
Infant: UTI, Flank mass, failure to thrive, sepsis
Adult: UTI, Flank pain, colicky pain, hematuria
Renal ultrasound, intravenous pyelogram. Palpation for hydronephrosis?
