Embryology - Urinary System Flashcards
What does the paraxial mesoderm form?
Somites
What does the intermediate plate mesoderm form?
Urogenital system (kidneys and repro.)
What does the lateral plate mesoderm form?
Body cavity and coverings
What is the position of the intermediate mesoderm?
Retroperitoneal position
What is the allantois?
Outpouching of the endoderm at the hindgut that extends into body stalk
What is the cloaca?
Single posterior opening at hindgut
In birds - for birds digestion, urinary and reproduction tracts are together
What is the cloaca divided into?
Rectum posteriorly
Urogenital sinus anteriorly
What separates the cloaca?
Urorectal septum
What forms the urinary bladder?
Urogenital sinus
What happens during the 4th week to the intermediate mesoderm?
In neck region becomes pronephros
What is the pronephros?
Pronephric duct and rudimentary pronephric tubules
Pronephric duct drains into cloaca
Rudimentary kidneys
When does the pronephros degenerate?
By 5th week except the pronephric duct
What is the mesonephros?
Intermediate mesoderm in trunk region
Late in week 4
Pronephric duct becomes mesonephric duct
Mesonephric tubules develop and drain into mesonephric duct
How long does the mesonephros function as the kidney?
Approx. 4 weeks
When does the metanephros (definitive kidney) develop?
From about 5th week but starts to function around week 9
What does the metanephros consist of?
A ureteric bud that comes off the mesonephric duct
Metanephric mesoderm - caudal part of intermediate mesoderm
What happens to the mesonephros?
Much of it will be incorporates into developing gonad
Undifferentiated cells from yolk sac migrate in to form spermatogonia/ oogonia
What does the mesonephric tubules and duct become?
Tubule - rete testis
Duct - vas deferens
In females - ovary but tubules and duct degenerate
Describe the further development of the ureteric bud
Undergoes repeated branching at its distal end
Stalk becomes ureter and the expanded cranial end becomes the renal pelvis
What does the 4 generations of branches of ureteric bud become?
First 4 become confluent to become major calyces
Next 4 form minor calyces
Remaining become the collecting tubules
What forms the kidneys?
Metanephric membrane from the intermediate plate mesoderm
What does the nephron consist of?
Renal corpuscle + PCT + loop of Henle + DCT
What does the uriniferous tubule consist of?
Nephron + collecting duct
What develops from the ureteric bud?
Collecting duct and calyces, pelvis and ureter
Describe the ascent of the kidneys
Initially lie on either side of bladder and in developing pelvis
Kidneys come to lie in upper abdomen - T1-L3
Hilum rotates ventral to medial
Stops when come in contact with adrenal glands
Differential growth of lower body inferiorly away from kidneys
What is the relationship between the ureteric bud and metanephric mesoderm?
Reciprocally induce each other
