Embryology Of Urinary System Flashcards
What are the 3 kidney systems that form during development?
Pronephros
Mesonephros
Metanephros
What do the kidneys arise from?
Intermediate mesoderm
What does the bladder arise from?
Endoderm
Outline the Pronephros development
- arises from intermediate mesoderm
- the first kidney system that develops
- has no function in humans > degenerates
- Pronephric duct extends from the cervical region to cloaca
- this drives the development of the Mesonephros
Outline the mesonephros development
- step two
- develops below degerenating pronephros (in the thoracic-lumbar regions)
- mesonephric tubules develop off the mesonephric duct
- filtration function but no water conserving function > needs to upgrade
What forms the Embyronic kidney?
Mesonephric tubules
Mesonephric duct
Importance of the mesonephric duct
- Development of the male reproductive system
- Sprouts ureteric bud > induces development of definitive kidney
Outline the Metanephros
- step three
- ureteric bud forms at the lower portion of the mesonephric duct > froms the collection system
- induces differentiation of intermediate mesoderm (metanephric blastema) > forms excretory portion of the kidneys
Location of the different stages of development of the urinary system
- pronephros: cervical region
- mesonephros: thoracic - lumbar region
- metanephros: lower lumbar - sacral region
What forms the collecting system?
Ureteric bud
What forms the excretory portion (nephrons) of the kidneys?
Differentiation of the metanephric blastema (intermediate mesoderm)
What can go wrong in the development of the renal system?
- ureteric bud fails to interact with intermediate mesoderm > renal agenesis
- migration goes awry
- duplication defects
- ectopic ureter
- cystic disease
- horseshoe kidney
- pelvic kidney
Renal structural anomalies related to migration
Pelvic kidney
Horseshoe kidney
How does pelvic kidney arise?
Kidney hasn’t ascended correctly
Gets caught on vessels during ascent
How does horseshoe kidney arise?
- fusion at bottom of kidneys during ascent
- forms a horseshoe shape
- get caught on the inferior mesenteric artery > do no ascend as high
How do the kidneys ascend?
What is a common occurrence due to this?
- Kidneys ascend by creating branches off the aorta as it rises up
- presence of accessory renal arteries left over from ascent
What abnormalities of the ureter can occur during development?
- splitting of ureteric bud > duplication
- partial development
- can cause ectopic ureteral opening
How is the urogenital sinus formed?
What occurs after this?
- Splitting of cloaca by urorectal septum
. - superior part connnects to umbilicus > differentiates to urinary bladder
- inferior part > urethra
Difference in differentiation of inferior part of urogenital sinus in men and women
- women: entire urethra + clitoris
- men: membranous + sponges urethra
What week is the kidney functional in utero?
Week 10
