Embryology Flashcards
Which layer of mesoderm becomes the kidneys and reproductive system (urogenital system)
Intermediate plate mesoderm
What does the cloaca divide to form?
Rectum (GI tract) and anteriorly the Urogenital Sinus.
What drains into the urogenital sinus?
Mesonephric duct
What does the urogenital sinus later form?
The urinary bladder and its caudal end forms the urethra
How many sets of kidneys develop sequentially during nephrogenesis?
3
In which week does the intermediate mesoderm become the pronephros?
week 4
What is the Pronephros?
Made up of the pronephric duct + rudimentary pronephric tubules
First epithelial structure formed within the intermediate mesoderm
What does the pronephric duct drain into?
The cloaca
When do the pronephros degenerate (except the pronephric duct)?
Week 5
What was the Mesonephric duct originally?
The pronephric duct
What is the mesonephros and what does it function as for approx 4 weeks?
It is Intermediate mesoderm in trunk region, late Week 4.
Functions as the kidney
When do the metanephros start to develop and when do they then start to function?
Develop at bout week 5
start to function around week 9
What does the metanephros consist of? (2)
A ureteric bud that develops off the mesonephric duct
Metanephric mesoderm (the most caudal part of the intermediate mesoderm)
What happens to the mesonephros?
Most will be incorporated into the developing gonad
What do the mesonephric tubules become?
The rete testis
What does the mesonpheric duct become?
Vas deferens
What happens to the mesenephros and mesonephric duct in females?
The mesnephros becomes the ovary but the tubules and mesonephric duct degenerate
The ureteric bud undergoes repeated branching at its distal end. What does it become?
The stalk becomes the ureter and the expanded cranial end becomes the renal pelvis.
What do the first 4 generations of branches from the ureteric bud become?
They merge to become the major calyces
What do the next 4 generations of branches from the ureteric bud become? (after the first 4)
Minor calyces
The remaining generations of branches formed from the ureteric bud become what?
Collecting tubules
What does the nephron consist of?
Renal corpuscle + Proximal CT + Loop of Henle + Distal CT
What does the Uriniferous tubule consist of?
Nephron and collecting duct
What does the nephron develop from?
Metanephric mesoderm
What do the Collecting duct and calyces, pelvis and ureter develop from?
Ureteric bud
What level do the kidneys lie at
T12-L3
When do the kidney’s stop ascending during development?
When they come into contact with the adrenal glands
Allantois and cloaca form what?
The urinary bladder and urethra
Summary
- Allantois and cloaca => urinary bladder and urethra
- Intermediate mesoderm develops into the rudimentary pronephros in neck (week 4), Mesonephros in trunk region (week 5 to 9) with a duct and tubules. Duct drains into cloaca
- Ureteric bud grows out of the caudal end of the mesonephric duct…
- . …and branches to form the renal pelvis, calyces and collecting duct
- The ureteric bud and the metanephric mesoderm reciprocally induce each other
What does the paraxial mesoderm form?
Somites
What does the lateral plate mesoderm develop into?
Body cavity and coverings
