Renal Embryology Flashcards
what embryonic cell type does the kydneys give rise from
Intermediate mesoderm
also will give rise to the gonads as well but the urinary system develops first
where is the Intermediate mesoderm located on the trilaminar disk
found inbetween the paraxial mesoderm and the lateral plate mesoderm
what structure does the urogenital system give rise from
the urogenital ridge: longitudinal band of mesoderm that forms on each side of the dorsal aorta
what develops from the urogenital ridge and what structures does this give rise to
the urogenital ridge will give rise to the nephrogenic cord
this will give rise to the nephric structurues:
- pronephros
- mesonephros
- metanephros
what is the development progression of the kidney
Urogenital ridge Nephrogenic cord Pronephros mesonephros metanephros
Function and characteristics of the Pronephros
Bilateral transitory structures
- appear in 4th week
- Located in cervical region
Pronephric ducts run caudally and open into the cloaca
degenerate by 24-25 days
But pronephric ducts persist and are used by the mesonephros
important for the initiation of the cascade that leads to the formation of the definitive kidney
Function and characteristics of the Mesonephros
Bilateral transient structures
- appear late 4th week
- caudal to pronephros
Includes the mesonephric ducts and tubules
- ducts develop 1st
- induce tubules from surrounding intermediate mesoderm
what do the mesonephric tubules form? and how long do they function
form the renal corpuscles
- medial end of the tubules is a cup shaped, glomerular capsule
- wraps around the glomerulus
Function as the interm kidneys from 6-10 weeks and produce small amounts of urine
after 10weeks stops functioning:
- will regress in females
- will form efferent ductules in males
- Degenerate by 12 weeks
what makes up the metanephros
Ureteric bud: outgrowth of mesonephric duct
Metanephric blastema: from the nephrogenic cord
when does the mesonephric duct arise and what does it induce
arises during the 5th week: the caudal end of each mesonephric duct near the cloaca will induce the uteric bud
when does the kidney functionally and definitively form and what is its main function
9-10th week, will have an excretory and collecting portion
main function is to make amniotic fluid
In the fetus the placenta gets rid of all the waste, not the fetal kidney
what happens to the ureteric bud and how is the collecting system formed
the Ureteric bud will elongate and penetrate the blastema to form the renal pelvis
the stalk of the ureteric bud will become the ureter
The cranial part of the bud will branch and create the collecting tubules
- 1st generations (4) of tubules will enlarge to be the major calices
- 2nd generation (4) of tubules will become the minor calices
5 steps of the nephron development
1) arched collecting tubule induces cells of metanephrogenic blastema to form metanephric vesicles
2) Vesicels will elongate to form metanephric tubules
3) Proximal end will form glomerular capsule, this will be invaded by glomeruli (blood vessels)
4) other end of the tubule lengthens and differentiates to PCT, DCT, and nephron loop as it lengthens
5) each DCT contacts an arched collecting tubule = now connected once fused at site of contact
repeat millions of times
Does the kidney develop anymore nephrons after birth
no, whatever you have after birth is what you have for life
will have to go on dialysis
how does the kidneys ascend
Permanent kidneys lie within the pelvis and will gradually ascend into the abdomen due to the caudal elongation
- mesonephros will degenerate as well
- Hilum rotates medially by 90 degrees
- 9th week will be in suprarenal glands
what is the vasculature of the kidneys
Recieve blood supply from the vessels that are the closest
The first branch is from the common iliacs but as thwe kidneys ascend, the definitive renal arteries from the aorta will form and give the blood supply
the former branches will undergo involution and disappear
Ureteric bud Embryonic structure gives rise to what adult structures?
Collecting portion
Ureter
Renal pelvis
Major and minor calyces
collecting ducts
Them metanephric blastema will give rise to what adult structures
Excretory Portion
Bowmans capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Unilateral renal agenesis
1:1000 more frequent in males
typically asymptomatic
lose a kidney
suspected in infants with 1 umbilical artery
Bilateral renal agenesis
1: 3000
Oligohydraminos
Nonviable-pulmonary hypoplasia
Potter syndrome
Duplications and the two types
Abnormal division of ureteric bud
Incomplete divison= divided kidney and bifed ureter
Complete division: double kidney and bifed ureter or separate ureters
Horseshoe kidney
fusion of the inferior poles
asymptomatic
ascent can be prevented by Inferior mesenteric Artery
Accessory Renal vessels
multiple renal arteries
-25 percent of adult kidneys
2x common as accessory veins
can obstruct the ureter and cause hydronephrosis
if ligated can cause ischemia
Polycystic kidney disease
Autosomal recessive mutation of PKHD1
cysts present in both kidnes
renal insufficiency
25% associated with pulmonary hypoplasia
Multicystic kidney disease
abnormal development of renal system
cysts are likely dilations of loop of Henle
normally only one kidney affected
What is the Urogenital sinus and what is its three parts
Ventral cloaca (distal hindgut) contains the urogenital sinus and the anorectal canal -these regions are seperated by the urorectal septum
the urogenital sinus is critical for bladder and urethral development
- vesical part - forms most of the urinary bladder
- pelvic part - forms neck of bladder and prostatic urethra (m) and urethra (f)
- Phallic part - forms the spongy urethra (m) and lining of the vaginal vestibule (f)
sequence of the development of the connections to the bladder, and the trigone
between 4-6 weeks the mesonephric duct is incorporated into the posterior wall of the bladder
-uretric bud is also attached which will connect the openings of the ureteric buds into the bladder wall
openings of the mesonephric duct are carried inferiorly to the pelvic urethra
Forms the trigone, triangular region of the mesonephric and ureteric ducts that blend into the posterior bladder
Bladder development and what tissues comes from what embryologically
Develops mainly from the vesical part of the urogenital sinus
Epithelium = endoderm (urogenital sinus)
Submucosa and muscularis = splanchnic mesoderm
Trigone = intermediate mesoderm (mesonephric ducts)
since the bladder is continuous with the allantois, what happens to it during the development of the bladder
the allantois will constrict and form the urachus
- which extends from the apex of the bladder to the umbilicus
- happens as the superior portion of the bladder is established
then will form the median umbilical ligament still in our bodies today
Exstophy of the bladder
ectopic vesicae
arises during the body folding during the 4th week
defective closure of the ventral abdominal wall
exposure of mucosa of the posterior wall of bladder
Epispadis
urethral opening is on the dorsum of the genital tubercle rather than on its ventral side
can occur with the exstrophy of the bladder
what are the three different Urachal Anomalies
Urachal cysts: reminants of the epithelial lining of the urachus that can become infected and enlarged
Urachal sinus: end of the urachus remains open into the bladder (inferior region) or umbilicus (superior region)
Urachal fistula: entire urachus remains patent and allows urine to escape from umbilical orifice
-leaking urine or discharge
what are the three layers of the cortex and what do they secrete
medulla?
Zona glomerulosa: produces mineralocorticoids (regulate electrolytes)
Zona fasciculata: produces gluccocorticoids (regulate blood glucose, lipid metabolism)
ZOna reticularis: produces sex hormones, estrogen, and testosterone related hormones
Medulla: chromaffin cells which secrete NE and epi
Development of the suprarenal gland
1) 5th week, coelomic epithelium delaminates and enters surrounding mesoderm to the fetal cortical cells
2) Neural crest cells will migrate into the medulla and differentiate to make the chromaffin cells
3) fetal cortex regresses (2nd month PN) and definitice cortical cells reorganize to make the zona glomerulosa, fasciculata, and reticularis (adult)
- come from the urogenital ridge
What does the fetal cortex secrete from the suprarenal gland that is important for the mother
secretes dehydroepiandrosterone (DHEA) which is converted by the placenta to estradiol
helps in maintaing pregnancy and also secretes ACTH and gluccorticoids
what is the embryological cell type that the capsule, cortex, and medulla come from in the suprarenal gland
capsule: mesonephric mesoderm
cortex: coelomic epithelium (somatic mesoderm)
medulla: NCC
