Development of the Urinary System | B2, WK5 Flashcards
The urinary (and genital) system is derived from what?
Intermediate mesoderm (intermediate mesenchyme)
What does the urogenital ridge differentiate into?
nephrogenic cord and genital ridge
What does the nephrogenic cord eventually form?
Mesonephros
What three excretory organs does the nephrogenic cord give rise to?
Pronephros
Mesonephros
Metanephros (permanent kidney)
Describe the pronephros
Shows up, then immediately leaves (blame evolution)
Describe the mesenephros
Int. Mes. of upper thoracic to 3rd lumbar
Mesonephric duct runs from it to the urogenital sinus
Produces small amounts of urine (between wks 6-10)
Disappears by wk 10
Describe the metanephros
Forms adult kidney
Attaches to UG sinus via ureteric bud
What two structures does the metanephros form?
1- ureteric bud
2- metanephric mesoderm (metanephric blastema)
What does ureteric bud develop into?
-collecting tubules
-ducts of kidney
-ureter
-Renal pelvic
-Major/Minor calyces
What does the metanephric mesoderm develop into?
-glomerular capsules
-proximal convoluted tubules
-nephron loops
-distal convoluted tubules
The uretic bud begins to differentiate at the start of week 5. The initial bulging turns into what structure? And then what structures form (weeks 6-7)?
Renal pelvis
After that, the major calyx and minor calyx develop.
By the 10th week, the collecting tubules and _____________ fuse, creating what?
Nephron
Created pathway for urine to leave kidney (so kidney is then functional)
T/F: During weeks 6-9, the kidney descends from the lumbar to pelvis region
F: Ascends from pelvis to lumbar region
What is a unilateral renal agenesis?
When one kidney fails to develop
What could cause a renal agenesis?
Arises if interaction between ureteric bud and mesoderm fails to occur
What is bilateral renal agenesis?
Both kidenys fail to develop - this is fatal
If someone suffers oligohydramnios during pregnancy, what could this be a sign of?
Bilateral Renal Agenesis
Oligohydramnios: Disorder of amniotic fluid resulting in decreased amniotic fluid volume for gestational age
What is potter sequence?
What is a pelvic kidney? What would be the kidneys blood supply?
One/both kidneys fail to migrate.
Blood supply: Common iliac artery
**Note, kidneys work fine and this is typically asymptomatic
What is a horseshoe kidney?
Lower parts of L and R kidney fuse together
As kidney starts to migrate up, it gets caught on IMA
**Note, kidneys work fine and this is typically asymptomatic
What is a bifid ureter?
Ureter duplication
-May be partial (Y-pattern) or complete (2 separate ureters)
What is a supernumerary kidney?
The supernumerary kidney is kidney in addition to two kidneys. It may or may not be fused to the other kidneys. Only a few case reports are in literature.
When would a kidney have multiple renal vessels?
If temporary vessels (from ascending) fail to regress
(this is fairly common)
Contrast a intravenous pyleogram from a retrograde pyleogram
Intravenous: contrast injected into veins
retrograde: contrast injected into urethra
What is hydronephrosis?
Distention of kidney with urine
**caused by obstruction to urine flow
(can be diagnosed via ultra sound)
What could be some causes of hydronephrosis?
-Tumor/cancer
-Pregnancy
-Kidney stones
-Vesicouretral reflux (reflux of urine from bladder back into ureters)
Are simple kidneys cysts asymptomatic?
usually!
What is PKD?
Genetic disorder causing numerous kidney cysts
Eventually interfere with normal kidney function
Cysts can migrate to liver (PLD)
RECALL: what is included in the hindgut?
Rectum, sup. anal canal, epithelium of urinary bladder, most of urethra
The expanded distal end of the hindgut is known as
Cloaca
What is the cloacal membrane?
Separates cloaca from outside of the body
Allantois
Cloaca –> umbilicus
What does the anterior part of the cloaca form? what about the posterior?
Anterior: forms urogenital sinus (epi. of bladder, most of urethra, allantois)
Posterior: anorectal canal (rectum + sup. part of anal canal)
What does the urorectal septum separate?
Cloaca into ant. urogenital sinus and post. into anorectal canal
After week 7, the urorectal septum is done dividing. It then fuses with part of the cloacal membrane. What is formed?
Perineal body (central tendon of the perineum)
What is the cloacal membrane subdivided by perineal body into?
-ant. urogenital membrane
-post. anal membrane
(these membranes rupture after wk. 8)
What forms the bladder and most of the urethra?
Cloaca (endoderm) and splanchnic mesoderm
[Cloaca = epithelium, splanchnic = muscles and CT]
What is anorectal agenesis (anal agenesis)? What causes it?
Rectum ends in blind pouch
Caused by abnormal urorectal septum formation
What is an imperforate anus?
Anal membrane fails to rupture
What is the function of the cortex [adrenal glands]?
Secretes corticosteroids (hormones that regulate salt, sugar, or sex)
What is the function of the medulla [adrenal glands]?
Secretes epinephrine and norepinephrine (prolong effects of sympathetic ANS - fight/flight)
What is the adrenal cortex formed from?
Intermediate mesoderm (from urogenital ridge)
What is the adrenal medulla formed from?
Neural crest cells (that migrate to + penetrate deep to the cortex)
In the adrenal medulla, what do neural cells differentiate into?
Chromaffin cells of the medulla
