Urinary Embryology Flashcards
What is the urinary system derived from?
Intermediate mesoderm - urogenital ridge
How does the urinary system develop?
Sequentially - overlapping systems
What are the stages of urinary development?
Pronephros
Mesonephros
Metanephros
What is the first stage of urinary development?
Pronephros
When does the pronephros first appear?
Week 4
What region of the embryo does the pronephros form?
Cervical region
What happens in the pronephros stage?
Nephrotomes formed from intermediate mesoderm
Nephrotomes join into pronephric duct
Where does the pronephric duct lie?
From cervical region to cloaca
What is the second stage of urinary development?
Mesonephros
Where does the mesonephros develop?
Caudally to pronephros
What happens in the mesonephros stage?
Presence of pronephric duct induces formation of mesonephric tubules
Mesonephric tubules drain into mesonephric duct
Mesonephric duct sprouts the ureteric bud
What is the mesonephric duct?
Continuation of the pronephric duct
What acts as the embryonic kidney?
Mesonephric tubules + mesonephric duct
What is the third stage of urinary development?
Metanephros
When does the metanephros appear?
Week 5
What does the metanephros form?
Definitive kidney
When is the metanephros fully functional?
Week 12
What happens in the metanephros stage?
Mesonephric duct makes contact with the metanephric blastema to form the metanephric system
What are the components of the metanephric system?
Collecting system
Excretory system
What is the collecting system derived from?
Ureteric bud
What happens in the collecting system?
Dilates to create
- ureter
- renal pelvis
- major + minor calyces
- collecting tubules
What is the excretory system derived from?
Metanephric blastema
What happens in the excretory system?
Each collecting tubule covered by a metanephric tissue cap - gives rise to excretory tubules
Excretory tubules form the nephron
- proximal end = bowmans capsule
- distal end = PCT, LoH, DCT
What structure forms the bladder and urethra?
Cloaca
