Embryology Urinary tract Flashcards
what is the primary origin of the urinary system
intermediate mesoderm
what is the first set of kidneys that form
pronephros
form in thorax (from nephrogenic ridge)
these form during beginning of week 4 and are gone at the end of week 4
not very important at all b/c no congenital abnormalities come from this
what is the second set of kidneys
Mesonephros
form week 4 and become functional nephrons and function until about month 3
these tubules drain into the mesonephric duct
from in lower thoracic upper lumbar region
excrete products into mesenphric duct
what in males does the mesonehric duct contribute to form
genitalia of males
what is the third set of kidneys
when does it form
Metanephros
forms week 5, functional by end of third month
this is the definitive kidney (adult kidney)
forms in the pelvic region
has both the metanephric blastema (from intermediate mesoderm in the pelvis)
AND the ureteric bud (forms ureter which is a diverticulum that forms from the mesonephric duct)
at the 3rd month
what does the metanephric blastema form?
Nephron (excretory units of the kidney)
bowman’s capsule
proximal convoluted tubules
loops of henle
distal convoluted tubules
what does the ureteric bud form?
the ureteric bud is an evagination of mesonephric duct and penetrates the metanephric blastema
Forms: collecting tubules minor and major calyces renal pelvis ureter
WT1
wilm’s tumor protein 1
one of the most important proteins involved in the development of the kidney (reciprocal stimulation)
if the ureteric bud or the nephron don’t signally properly the kidney WONT form correctly
what movement do the kidneys undergo around 6 weeks - 9 weeks
what happens to their blood supply as they ascend
ascent and rotation from the pelvis into the abdomen (upper part)
in the pelvis the hilum is directed anterior then these rotate about 90 degrees medially as they ascend so that the hilum faces anteromedially
as they ascend they receive new blood vessels, lymphatics, and nerves*** (only organ that does this)
orginal blood supply is from the common iliac arteries
The permanent renal arteries are branches of the aorta
caudal arterial branches typically degenerate
LV1 LV2
renal artery
what is the shape of the fetal kidney
lobulated
when the infant is born these will be smooth
what does the cloaca form
the urinary bladder and urethra
what does the urorectal septum divide
divides the cloaca into the anterior urogenital sinus and the posterior rectum/anal canal
the allantois forms what?
has attachment to the urogenital (Cranial portion) part of the cloaca (but is endoderm derived)
eventually it forms the urachus (more fibrous)
the urachus will form the median umbilical ligament which remains attached to the urinary bladder
where does the trigone come from
what is its function in the bladder
the mesonephric duct
this is because the mesenephric duct grows to become part of the bladder itself
trigone then acts as a sphincter mechanism for the ureter!!
what is the cause of accessory renal arteries/veins
what happens if this is symptomatic
how do you fix
more caudal vessels fail to regress during ascent of the kidney
usually asymptomatic
(these arteries are end arteries so they must be transposed and cannot just be removed b/c then you would lose blood supply to an entire segment of the kidney)
accessory vessels can cause compression of ureter and become symptomatic
what is the cause of renal hypoplasia
when is the symptomatic
Inadequate branching of ureteric bud and lack of differentiation of nephrons
(underdevelopment of the kidney)
symptomatic if this is bilateral!!
what are the cystic disease and when are they present?
in autosomal recessive cyst form from what
in autsomal dominant cyst forms from what
the functional part of the kidney is replaced by cysts
Both of the following are types of this that are PRESENT AT BIRTH ***
Multicystic dysplastic
Polycystic kidneys
recessive –> from from collecting ducts
dominant–> from collecting ducts and nephrons
what is the cause of renal agenesis
No kidney formation BUT with most of these the adrenal gland is fine b/c it has a different embryological origin
cause:
Ureteric bud fails to form and/or induce differentiation of the metanephric blastema.
unilateral –> asymptomatic
what are the of horseshoe kidney and pelvic kidney
pelvic (ectopic) kidney- fails to ascend
horsehoe kidney–> Inferior poles of left and right kidneys fuse in the pelvis. Ascent is blocked by inferior mesenteric artery.
usually these are asymptomatic!
completely functional kidneys just in a different spot
what is Wilm’s tumor
presents by year 5 ( very malignant)
metastases to the lung
caused by mutation in the WT1 (which is expressed in the metanephric blastema)
this results in metablatic blastima that is very underdifferentiated but very rapidly dividing tissue (cancer tissue)
will also see gonad that doesn’t form b/c of Deny’s -Drash syndrome which is what wilm’s tumor is part of
WAGR syndrome
mutation of WT1 and PAX6 (even more severe than WIlm’s tumor)
Pax6 is involved in brain and eye development
aniridia (no eye) and mental retardation
what is the cause of the duplication of the ureter
splitting of the ureteric bud causing a y-shaped ureter
can lead to duplication of the kidney
what is the cause of an ectopic ureter
two ureteric buds form
usually the lower portion is normal
the upper of the two ureters is often abnormal (dilated, less smooth muscle, drains to abnormal site)
