Embryology Flashcards
What are the components of the adult urinary system?
- Kidneys
- Ureter
- Bladder
- Urethra
- Blood supply
What are the components of the kidney?
- Nephron
- Collecting duct
- Calyces and pelvis
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 position does the intermediate mesoderm take?
Retroperitoneal
What is the allantois?
An out pouching of endoderm at the hindgut that extends into the body stalk
What does the body stalk later form?
Umbilical cord
Cloaca
The cloaca is the single posterior opening for a bird’s digestive, urinary and reproductive tracts and is used to expel faeces and lay eggs.
What does the cloaca divide to form?
- Posteriorly rectum (GIT)
- Anteriorly the urogenital sinus
What doe the mesonephric duct drain into?
Urogenital sinus
What does the urogenital sinus later form?
Urinary bladder and its caudal end forms the urethra
How many sets of kidneys develop during nephrogenesis?
3 sets of kidneys develop sequentially
What does the intermediate mesoderm in the neck region become early in the 4th week?
Pronephros
What is the pronephros made up of?
Pronephric duct and rudimentary pronephric tubules
What does the pronephric duct drain into?
Cloaca
What happens to the pronephros?
It mainly degenerates by week 5
What does the intermediate mesoderm in the trunk region become late in the 4th week?
Mesonephros
What does the pronephric duct become?
Mesonephric duct
What drains into the mesonephric duct?
Mesonephric tubules
When does the metanephros start to develop?
About week 5
When does the metanephros start to function?
About week 9
What does the metanephros consist of?
- A ureteric bud that develops off the mesonephric duct
- Metanephric mesoderm (the most caudal part of the intermediate mesoderm)
What happens to the mesonephros?
Much of the mesonephros will be incorporated into the developing gonad
What do undifferentiated cells from the yolk sac migrate to form?
Spermatogonia/oogonia
What becomes the rete testis?
Mesonephric tubules
What becomes the vas deferens?
Mesonephric duct
What happens to the mesnephros in females?
In females the mesnephros becomes the ovary
What happens to the mesonephric duct in females?
The tubules and mesonephric duct degenerate
What happens to the ureteric bud at its distal end?
Undergoes repeated branching
What does the stalk of the ureteric bud become?
Ureter
What does the expanded cranial end of the ureteric bud become?
Renal pelvis
What do the first 4 generations of branches of the ureteric bud become?
Major calyces
What forms the minor calyces?
Generations 5-8 of the branches of the ureteric bud
What forms the collecting tubules?
The remaining branches (ones that haven’t formed the calyces) of the ureteric bud
What reciprocally induce each other?
Ureteric bud and the metanephric mesoderm
What are the components of a nephron?
- Renal corpuscle
- Proximal collecting tubule
- Loop of Henle
- Distal collecting tubule
What are the components of a uriniferous tubule?
- Nephron
- Collecting duct
What does the nephron develop from?
Metanephric mesoderm
What do the collecting duct, calyces, pelvis and ureter develop from?
Ureteric bud
Where do the kidneys initially lie?
Kidneys initially lie on either side of the bladder and in the developing pelvis
Why do the kidneys ‘ascend’ into the abdomen?
Mainly due to differential growth of lower body inferiorly away from kidneys
What is the final vertebral level of the kidneys?
T12-L3
How does the hilum of the kidney rotate?
From ventral to medial through 90 degrees
When does ascent of the kidneys stop?
When they come into contact with the adrenal glands
What happens alongside the ascent of the kidneys?
Segmental breakdown and reform of vascular supply
What anomalies may occur during development?
- Double ureters
- Abnormal sites of ureter opening
- Congenital polycystic kidneys
- Aberrant renal arteries
- Lobulated kidney
- Transposition of kidney
- Horseshow kidney
- Pancake kidney
How long does the mesonephros function as the kidneys?
Approx 4 weeks
