Renal Embryology

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  • Pronephros week 4 Forms then degenerations is part of the mesoderm layer
  • Mesonephros 3-12 weeks first trimester interim kidney, later becomes part of the male genital system Wolffian (vas Deferens)
  • Matanephros permanent, first appears weak 5, nephrogenesis continues through 32-36 weeks of gestation (third pregnancy weeks 28-)
  • Uteric bud- metanephric diverticulum (derived from caudal end of mesonephric duct) rise to ureter pelvis, calyces, collecting duct Fully canalized 10th week
  • Metanephric mesenchyme-metanephric blastema: Uteric bud interacts with this tissue, differentiation and formation of glomerulus through distal convoluted tubule
  • Aberrant interaction with metanephric diverticulum and metanephric blastema - leads to renal genesis, multi cystic dysplastic kidney
  • Ureteropelvic junction last to canalize-> congenital obstruction. Most common cause of prenatal hydronephrosis. Detected by prenatal ultrasound
  • Potter sequence symptoms from Oligohydramnios- compression of developing fetus, limb deformities, facial anomalies, low set sears, retrgnathia (chin back), flattened nose
  • Potter sequence includes: pulmonary hypoplasia #1 death,  CAUSES: autosomal recessive polycystic kidney disease (ARPKD), posterior urethral vales/obstructive uropathy, renal genesis, chronic placental insufficiency- Fetal blood of placenta compromised or thin placenta providing not enough nutrients--> hypoglycemia, hypoxemia, high infection rate possible less B cells WBC, polycythemia, 
  • Horseshoe kidney: Kidney usually T12-L3. Associated with increase risk if renal cancer like Wilms tumor, hydronephrosis (uteropelvic junction obstruction, Renal stones) infections, Higher incidence in chromosomal aneuploidy, Symphyiostostmy but now recommended, kidneys can stay in same spot after surgery
  • Congenital Solitary Functioning Kidney: Being born with one kidney. Compensatory hypertrophy of contralaterlal kidney. Diagnosed prenatally with ultrasound- focal segmental Gomerular sclerosis occurs
  • Unilateral renal genesis: uteric bud fails to develop and induce differentiation of metanephric mesenchyme complete absence of kidney and ureter. 
  • Multi-cystic dysplastic kidney: Ureteric bud fails to induce differentiation of metanephric mesenchyme---> nonfunctional kidney consisting of cysts and connective tissue. Predominantly nonhereditary and usually unilateral bilateral to cause Potter sequence
  • Duplex collecting system: Bifurcation of ureteric bud before it enters the metanephric blastema, creates a Y shape bifid ureter. Duplex collecting system can alternatively occur through two ureteric buds reaching and interacting with metanephric blastema. Increases vesicoureteral reflux or ureteral obstruction. Backward flow from bladder into kidney, increase UTIS
  • Posterior urethral valves: Membrane remnant in the posterior urethra in males. Its persistence can lead to urethral obstruction. Can be diagnosed prenatally by bilateral hydronephrosis and dilated or thick walled ladder. Common cause of bladder outlet obstruction. Associated with Oligohydramnios

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