Embryology of the Urinary System Flashcards
Which part of the mesoderm does the urinary system develop from?
Intermediate plate mesoderm
What is the allantois?
The outpouching of endoderm at the hindgut that extends into the body stalk
What is the cloaca?
The single posterior opening for the birds digestive, urinary and reproductive tracts: used to expel faeces and lay eggs
What structures are formed when the cloaca divide?
Rectum and urogenital sinus
Which duct drains into theurogenital sinus?
Mesonephric
What does the urogenital sinus develop into?
The bladder (the caudal end also does forms the urethra
What happens to the intermediate mesoderm in the neck during week 4?
It forms the pronephros
What structures make up the pronephros?
Pronephric duct + rudimentary pronephric tubules
Where does the pronephric duct drain?
The cloaca
What happens to the pronephros in humans?
The pronephros mainly degenerates by week 5 except the pronephric duct
What are the mesonephros?
Intermediate mesoderm in the trunk (late week 4)
What happens to the pronephric duct?
It becomes the mesonephric duct
What structures drain into the mesonephric duct?
Mesonephric duct
What is the function of the mesonephros?
They function as kidneys for approx. 4 weeks
What are the metanephros?
The definitive kidneys
At what point do the metanephros develop and when do they start to function?
Develop Begins: Week 5
Function: Week 9
What do the metanephros consist of?
A ureteric bud (develops off the mesonephric duct) and the metanephric mesoderm
What happens to the mesonephros?
Most of the mesonephros will be incorporated into the developing gonad
What happens to the mesonephric tubules?
It becomes Rete testis
What happens to the mesonephric duct?
It becomes the vas deferens
What happens to the mesonephric tubules and duct in females?
They degenerate
How does the ureteric bud further develop?
It repeatedly branches at its distal end
What structures do the stalk and the expanded cranial end of the ureteric bud form?
Stalk: ureter
Expanded cranial end: renal pelvis
What do the first four generations of branches of the ureteric bud form?
Major calyces
What do the 2nd four generations of the branches of the ureteric bud form?
Minor calyces
What do the remaining generations of the ureteric bud branches form?
Collecting tubules
Is a nephron and uriniferous tubule the same thing?
No
Nephron = renal corpuscle + PCT + loop of henle + DCT
Urniferous tubule = nephron + collecting duct
Where do the kidneys initially lie?
On either side of the bladder
What happens to the kidneys as the foetus develops?
They appear to ascend into the abdomen mainly due to the growth of the lower body away from the kidneys
Where do the kidneys eventually end up?
Upper abdomen (T12-L3)
What stops the ascent of the kidneys?
When they come into contact with the adrenal gland
