Flashcards in Embryology Of Urinary System Deck (22)
What are the 3 developmental stages of the kidneys?
When is the primordium of the gut formed?
During embryological folding
(Endoderm lined tube suspended within a cavity)
Name the 2 areas that have no mesoderm after gastrulation
Buccopharyngeal membrane (cranial)
Cloacal membrane (caudal)
How do areas with no mesoderm become openings?
No mesoderm therefore no blood vessels
The avascular tissue dies to create an opening
Describe the pronephros
Appears in the cervical region (head and neck region)
Creates the pronephric duct which extends from the cervical region to the cloaca
Drives the development of the next stage
Describe the mesonephros
The stage that takes over from the pronephros
Occupies a trench within the entire trunk of the embryo
Takes over the use of the duct
Describe the metanephros
The true kidney
Appears in the pelvic region
What is a nephrotome?
A primitive/prototype nephron
What is the urogenital ridge?
Region of the intermediate mesoderm giving rise to both the embryonic kidney and the gonad
Where does the ureteric bud sprout from?
What is the role of the ureteric bud?
Development of the ureters
Induces development in caudal region on the embryo
Releases signals to the intermediate mesoderm
How can accessory renal arteries form?
As the kidneys move they sprout new vessels from the abdominal aorta. Usually the old vessels regress but if not then you get accessory vessels.
Splitting of the ureteric bud can lead to:
Another lobe of the kidney formed
2 kidneys on one side
Extra ureters (lead to ectopic ureteral openings)
What is the cloaca?
Where the GI, urinary and reproductive tracts all end early in development
What is the urogenital sinus?
Created from the hindgut by the formation of the urorectal septum (wedge of mesoderm that grows down)
Separates the urinary and GI tracts
Continuous with the umbilicus via the urachus
Divided into 3 sections
What are the 3 sections of the urogenital sinus called?
Upper (-> bladder)
Pelvic (-> urethra)
What is the adult derivative of the urachus?
Median umbilical ligament
Males retain which duct to form the vas deferens?
Name the parts of the male urethra
Membranous (above 3 = pelvic part of UGS)
Spongy (phallic part of UGS)
How does the spongy urethra form in men?
Genital tubercle elongate and genital folds fuse to form the spongy urethra
Driven by male sex hormones
Where does the urethra open in the female?