Embryology of Urinary System Flashcards
When does the urinary system form?
week 4
What are the two parts of the urogenital system?
- Urinary system
2. Genital system
From what tissue does the urogenital system originate?
intermediate mesoderm
T/F there are two slightly overlapping kidney systems?
False- there 3
What are the three kidney systems and what is their purpose?
Pronephros- rudimentary, nonfunctional
Mesonephros- function for a short time during early fetal period
Metanephros- forms the permanent kidney
When does the pronephros appear and degenerate?
Appears- day 21
Degenerates- day 24
When does mesonephros appear?
early week 4- usually when the pronephros degenerates
Where does the mesonephros develop/appear?
thoracic and lumbar segments of intermediate mesoderm
In week _ the thoracic segments regress but the mesonephric kidney continues to function until week __.
5
10
Urine travels from the mesonephros to the ____ via the ____ ____.
cloaca via the wolffian (mesonephric) duct
In which direction does canalization take place?
Caudally to cranially
Canalization initiates what?
The ureteric bud/metanephric diverticulum growth
What day does the collecting portion- the ureteric bud- occur?
day 28
The ureteric buds induce what?
the formation of metanephric blastema, which forms the glomeruli and tubules of the nephrons
What happens if there is no ureteric bud? What about extra ones?
Kidney doesn’t develop
Supernumerary kidneys
The stalk of the ureteric bud becomes what?
The ureter
The kidneys ascend, T/F
Truth!
When do the kidneys ascend?
Weeks 6-9
Initially they kidneys form near the _____ ___ of the embryo.
caudal end
Kidneys initially have their blood supply from the common iliac arteries. What happens during the ascent of the kidney?
New arteries will enter the hilum of the kidney
As kidneys ascend, do they drag their blood supply with them?
Nope, new vessels come in as the old ones degenerate
Pelvic kidney is the result of what?
The kidney doesn’t ascend- ectopic kidney
Horseshoe kidney is a result of what?
The kidneys fusing together and running into the IMA, so it’s a little lower
Supernumerary arteries of the kidney are a result of what?
… it’s fairly common, no big deal, as long as one of the extra arteries doesn’t push on the ureter
The cloaca in the hindgut becomes divided by the _____ ____.
Urorectal septum
The urorectal septum turns the cloaca into what two areas?
- Ventral urogenital sinus
2. Dorsal anorectal canal
The bladder forms from what portion of what?
The vesical portion of the urogenital sinus
The urethra comes from what part of what?
The pelvic part of the urogenital sinus
The distal portions of the mesonephric ducts and the attached ureteric ducts become incorporated into what?
The posterior aspect of the bladder
The spongy part of the urethra come from the ____ part of the urgogenital sinus
phallic
When the allatois is closed off/obliterated proximally, what is the obliterated part called?
The urachus
What is a urachal cyst?
Part of the allantois is closed off, then its open for a small pocket, and then it’s regular
What’s a urachal sinus?
It’s where the allantois is open and can drip urine out
What’s a urachal fistula?
It’s not a sinus and it’s not a cyst, but it’s kinda like the allantois was never obliterated- there is no urachus
