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Flashcards in Embryology Deck (20)
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What part of the mesoderm do the kidney and gonads come from?

Which one develops first?

Intermediate mesoderm

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?

Urogenital ridge

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?

Urogenital sinus

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?

Chromaffin cells
Respond to sympathetics to release epi/NE


What role does the fetal cortex of the suprarenal gland have in pregnancy?
What does this do?
What other things does the cortex release

Secretes dehydroepiandrosterone (DHEA)
Gets converted by placenta into estradiol, and is essential for maintaining pregnancy
ACTH & glucocorticoids