Renal Embryology Flashcards
What is DHEA and what is its importance?
secreted by fetal cortex –> converted by placenta to estradiol = essential for normal pregnancy
When do the metanephros arise?
during 5th week
When does the suprarenal gland develop in utero? how?
5th week: coelomic epithelium delaminates and enters surrounding mesoderm –> cortical cells –> NC cells migrate to medulla –> chromaffin cells
What are the major regions of the ventral cloaca?
What separates them?
urogenital sinus and anorectal canal are separated by urorectal septum
How do the major and minor calices form?
cranial part of ureteric bud branches –> collecting tubules first generations (4) of tubules –> major calices 2nd generations –> minor calices
How does the nephron form?
arched collecting tubules –> induce surrounding blastema to form metanephric vesicles –> elongate to form metanephric tubules –> proximal end = glomerular capsule; distal end differentiates into other tubules
What is a urachal fistula?
entire urachus remains patent and allows urine to leak out of umbilical hole
What are accessory renal vessels?
multiple renal arteries
~25% of adults
2x common as accessory veins
can obstruct the ureter –> hydronephrosis
What are the 3 sets of early nephric structures?
pronephros = first, rudimentary mesonephros = middle metanephros = permanent kidneys
What structures for from the ureteric bud? (4)
ureture
renal pelvis
major and minor calyces
collecting ducts
When do the mesonephros appear? When do they degenerate?
appear late 4th week function as interim kidneys from week 6-10 degenerate by week 12
How does the blood supply to the kidneys change in utero?
as kidneys ascend, renal arteries form, degenerate, and reform
first branch from common iliacs; definitive renal arteries are from abdominal aorta
What makes up the trigone?
residual mesonephric duct as it moves inferiorly and the ureteric duct
on posterior wall of bladder
What are the 2 types of kidney duplication?
caused by abnormal division of ureteric bud
incomplete division = divided kidney and bifed ureter
complete division = double didney and bifed ureter or separate ureters
What is a urachal sinus?
end of urachus remains open into pladder or umbilicus
body fluid can leak out of umbilicus
What is exstrophy of the bladder?
1:10-40000
abnormality of body folding in 4th week –> defective closure of ventral abdominal wall = mucosa of posterior bladder wall is exposed to outside
What is horseshoe kidney?
1:1000
fusion of inferior poles of kidney
asymptomatic
ascent prevented by Inferior mesenteric artery
What is a urachal cysts?
remnant of epithelial lining of urachus than can enlarge and get infected
What are the 3 parts of the urogenital sinus?
- vesical part: most superior, forms most of bladder
- pelvic part: forms neck of bladder; prostatic urethra and female urethra
- phallic part: most inferior; forms spongy urethra (m) and lining of vaginal vestibule (f)
What are the 3 zones of the cortex of the suprarenal gland?
zona glomerulosa: produces mineralcorticoids
zona fasciculata: glucocorticoids
zona reticularis: sex hormones
What type of germ tissue does the urinary system develop from?
intermediate mesoderm
When is the mesonephric duct incorporated into the wall of the bladder?
What happens when they are connected?
4-6 weeks
openings are carried inferiorly to the pelvic urethra —> forms the trigone w/ ureteric ducts
What is multicystic dysplastic kidney disease?
abnormal dev of renal system
cysts are likely dilations of loop of henle
one kidney affected (75%)
How do the permanent kidneys move in utero?
kidneys gradually ascend into the abdomen as pelvis elongates
hilum medially rotates 90 degrees
in adult position by 9th week
What is bilateral renal agenesis?
both kidneys dont form
due to oligohydramnios
20% of ppl with this have potter syndrome = visible facial deformities, etc assoc w oligohydramnios
What structures are induced from intermediate mesoderm in development of the urinary system?
urogenital ridge = raised area of intermediate mesoderm –> nephrogenic cord –> pronephros, mesonephros, metanephros
What germ layers do the parts of the bladder wall form from?
epithelium = endoderm (urogenital sinus)
submucosa and muscularis = splanchnic mesoderm
trigone = intermediate mesoerm (mesonephric ducts)
What happens to the suprarenal glands postnatally?
cortex regresses 2nd month PN –> difinitive cortical cells reorganize
What structure immediately precedes the ureter?
stalk of ureteric bud
What is unilateral renal agenesis?
missing a kidney bc ureteric bud doesn’t form or deteriorates too soon - no communication btw bud and blastema
typically asymptomatic
suspected in infants w/ 1 umbilical arter
1:1000, more frequent in males
What is epispadias?
urethral opening is on dorsum of penis rather than on ventral side
1:30000
What do the mesonephric tubules develop into?
renal corpuscles = glomerulus and bowman’s capsule
Where are the pronephros and what is their general structure and function?
bilaterally located in cervical region pronephric ducts run caudally and open into the cloaca *initiate the cascade leading to formation of definitive kidneys
What is hydronephrosis and what can it be caused by?
back up of fluid in kidneys
can be caused by an accessory renal artery that obstructs the ureter
When do the pronephros appear? when do they degenerate?
appear early 4th week degenerate by 24-25 days
What characterizes the medulla of the suprarenal gland?
in the middle
consists of chromaffin cells = postganglionic sympathetic neurons
secrete norepinephrine and epi
How does the metanephros arise?
caudal end of the mesonephric duct induces ureteric bud –> elongates and penetrates the metanephrogenic blastema
Where are the mesonephros and what is their general structure?
extend from thoracic to lumbar mesonephric ducts form first and extend down to cloaca –> induce tubules from surrounding intermediate mesoderm
What structures (4) form from the metanephric blastema?
(excretory portion)
bowman’s capsule
PCT
loop of Henle
DCT
What is the allantois and what happens to it during development?
endoderm continuous w/ bladder that originally goes out umbilical cord –> constricts and forms the urachus –> median umbilical ligament after birth
