3 Development of the Urinary Tract Flashcards
Embryology
What part of the developing embryo do the 3 separate kidney systems arise from initially?
Intermediate mesoderm
What is the name of the first kidney system to appear and where does it appear in the developing embryo?
Pronephros
in Cervical region
What is the function of the pronephric duct?
Pronephric duct extends from cervical region of cloaca and drives development of NEXT developmental stage
What is the urogenital ridge?
Region of intermediate mesoderm
Gives rise to:
- Embryonic kidney
- Gonad
Where do the mesonephric tubules (stage 2) develop relative to the pronephric region (stage 1)?
Mesonephric tubules caudal to pronephric region
What are the 2 main parts of the embryonic kidney?
Mesonephric tubules and mesonephric duct
What function does the emrbyonic kidney still lack (needs to develop)?
Water conserving function
Why are the mesonephros important (what do they do)? (2)
- Mesonephric duct- important role in development of male reproductive system
- Mesonephric duct sprouts ureteric bud- induces development of definitive kidney
What is the ureteric bud?
Undifferentiated intermediate mesoderm
(caudal to mesonephros)
What is the role of the uteric bud?
Induces development of true kidney
Describe the ‘ascent’ of the kidney (embryologically).
- Metanephric (embryonic) kidney in pelvic region
- Caudal–>cranial shift
- Crosses arterial fork (vessels returning blood from fetus to placenta)
List some major errors which can occur during the the development of the kidney.
- Uteric bud fails to interact with intermediate mesoderm
- Renal agenesis (if bilateral= not compatible with life)
- Migration goes awry
- Duplication defects
- Ectopic ureter
- Cystic disease
Name 2 structural abnormalites that can occur if migration goes wrong.
- Pelvic kidney
- Horseshoe kidney (gets stuck on arteries branching off aorta)
What can occur as a consequence of the ureteric bud splitting? (partial/incomplete)
Ectopic ureteral opening
What is the urogenital sinus and what does it do?
Tract created from hindgut by urorectal septum
- Superior part connects to umbilicus
- Middle (majority of it) differentiates to form bladder
- Inferior part- develops into urethra
What is the urorectal septum and what does it do?
Separates GI tract from urinary genital tract (urogenital sinus)
How does the urogenital sinus develop into the bladder and the urethra in females?
- Mesonephric ducts- reach urogenital sinus
- Ureteric bud sprouts from mesonephric ducts
- Urogenital sinus expands
- Mesonephric duct regresses
- Mesonephric duct regressed, ureteric bud opens into urogenital sinus
How does the urogenital sinus develop into the bladder and the urethra in males?
- Mesonephric ducts- reach urogenital sinus
- Ureteric bud sprouts from mesonephric ducts
- Smooth musculature begins to appear
- Urogenital sinus expands
- Ureteric bud and mesonephric ducts make independent openings in urogenital sinus
- Prostate and prostatic urethra formed
How is the spongy urethra formed in males?
- Gential tubercle elongates
- Genital folds fuse to form spongy urethra
(Differential development of external genitalia determined by presence of androgens)
(In females folds do not fuse)
From which part of the embryological structure are the prostatic and membranous urethra formed?
Narrowed lower segment of urogenital sinus
What is hypospadias?
Defect in fusion of urethral folds
Urethra opens onto ventral surface instead of end of glans
Fill in the missing labels in the following CT scan:
Complete the labelling:
Label arteries 1-5:
Where is the pelviureteric junction?
Area between renal pelvis and ureter
Describe the course of the ureter from the hilum until it enters the bladder. (5)
- Along anterior surface of psoas major (retroperitoneal)
- Passes under gonadal vessels (water under the bridge)
- Cross pelvic brim and enter pelvic cavity at sacroiliac joint
- Cross bifurcation of common iliac anteriorly
- At level of ischial spine, follows a transverse plane to enter bladder
Where is the vesoureteric junction?
Where ureter enters bladder
Where are the 3 common sites where renal stones can lodge? (3)
(Due to non-uniformity in lumen diameter)
- Pelviureteric junction
- Vesicoureteric junction
- Crossing iliac arteries
How long is the urethra in adults:
- Males
- Females
- Males: 20cm
- Females 4cm
The metanephros is the 3rd stage of the development of the kidneys. Why is it important? (2)
At this point:
- Collecting system develops from ureteric bud
- Excretory system develops from metanephric tissue cap
When do each of the 3 structure stages of the development of the kidney begin and end? (weeks)
- Pronephros: Start of week 4 - End of week 4
- Mesonephros: End of week 4- End of week 8
- Metanephros: Week 5–>
What is the urachus?
Median umbilical ligament in adults
What role does the hindgut have in the development of the urinary system?
Hindgut:
Creates urogenital sinus- from urogenital septum
Fill in the missing labels:
Which of the 2 highlighted areas is the collecting system and which is the excretory system? Where did they each develop from?
Why are there sometimes accessory or supernumery renal arteries?
As kidneys ascend- new arteries form and sometime old ones don’t degenerate- asymptomatic
If accessory renal arteries are terminal (end arteries) why might this be a problem?
No anastamoses- potential infarct
Fill in the missing labels:
Fill in the missing labels:
Fill in the missing labels 1 and 2:
What is the adult derivative of the urachus?
Umbilical ligament
What symptoms may present if the urachus fails to become the umbilical ligament?
- Urine exiting via umbilicus
- Cysts forming
