Flashcards in Embryology Deck (20)
What part of the mesoderm do the kidney and gonads come from?
Which one develops first?
Urinary system develops first
What is the first part of the urogenital system to form?
What does it give rise to?
What 3 things does that give rise to?
Each side of the dorsal aorta
A portion forms the nephrogenic cord
This gives rise to the pronephros, mesonephros, and metanephros
What happens to each of the three things that come from the nephrogenic cord?
Pronephros: rudimentary (dissolves), initiate the cascade leading to formation of definitive kidney.
Mesonephros: Functions briefly during early fetal period (in males will form efferent ductules)
Metanephros: Become the adult kidney.
What do the pronephric ducts run into?
The cloaca (latin for sewer)
What are the two parts that comes out of the metanephros?
1) Ureteric bud = outgrowth of mesonephric duct
2) Metanephric blasterma = from nephrogenic cord
The ureteric bud elongates and penetrates what? forming what?
The stalk of the ureteric bud becomes what?
The cranial part of the bud does what?
It elongates and penetrates the blastema (area around the nephrons) to form the renal pelvis
Stalk of the ureteric bud becomes the ureter.
The cranial part branches into collecting tubules
1st generation (4) -> forms major calices
2nd generations (4) -> minor calices
Where does the blood supply for the kidneys come from?
First branch form from common iliacs; definitive renal arteries are from abdominal aorta (former branches disappear).
Types of kidney abnormalities:
1) Unilateral renal agenesis
2) Bilateral renal agenesis
3) Duplications (in)complete
4) Horseshoe kidney
5) Accessory renal vessels
1) More frequent in males, typically asymptomatic, suspected in infants with 1 umbilical artery
2) Oligohydramnios, nonviable- pulmonary hypoplasia, potter syndrome (20%)
3) Incomplete = divided kidney & bifid ureter .... complete = double kidney & bifid ureter or separate ureters
4) fusion of inferior poles, asympotmatic, ascent prevented by IMA (stays low in the body)
5) Multiple renal arteries (25% of adults), 2x common as accessory veins, can obstruct the ureter > hydronephrosis, end arteries so bad if blocked.
What does the mesonephric duct become?
It attaches to the posterior bladder wall and becomes the trigone.
What do the mesonephric tubules wrap around?
They wrap around a glomerulus (knot of capillaries with high pressure that work to put fluid/plasma into the interstitium)
When does the mesonephros function as the "interim" kidney? What does it produce?
6-10 weeks, producing small amounts of urine
What one thing is "critical" for bladder and urethral development?
It has 3 parts what are they, and what do they become?
1) Vesical part: forms most of the urinary bladder
2) Pelvic part: forms neck of bladder; prostatic urethra (m) & urethra
3) Phallic part: forms spongy urethra (m) & lining of vaginal vestibule (f)
What does the bladder mainly derive from? (seen in other cards)
What kind of epithelium?
Vesical part of the urogenital sinus
Epithlium = endoderm
Besides the epithelium, what other embryonic progenitors contribute to the bladder?
Sumocosa & muscularis = splanchnic mesoderm
Trigone = intermediate mesoderm
What is the bladder continuous with? Describe this structure
With the allantois
* Developed from the hidgut
* Constricts and forms the urachus
* Extends from the apex of the bladder to the umbilicus
* Eventually constricts and forms the median umbilical ligament.
What is exstrophy of the bladder?
1) Exstrophy of the bladder
Arises during body folding
Defective closure of ventral abdominal wall
Exposure of mucosa of the posterior wall of bladder
What is epispadias of the bladder?
Urethral opening is on the dorsum of the genital tubercle rather than on the ventral side.
Can occur with exstrophy, but is rare
What are the 3 types of urachal abnormalities? Describe them.
1) Urachal cysts : remnants of the epithelial lining of the urachus that can become infected & enlarged.
2) Urachal sinus: end f the urachus opens into the bladder or umbilicus
3) Urachal fistula: entire urachus remains patent and allows urine out the umbilical orifice
What do neural crest cells become when they migrate into the medulla? What do they respond to?
Respond to sympathetics to release epi/NE