Embriology of UT Flashcards
Urinary System starts developing on…
Week 4
intermediate mesoderm forms…
urogenital ridges
Urogenital ridges will give rise to …
urinary and genital system
Nephrogenic cord
part of the urogenital ridge, which is what develops into the urinary structures
Nephrogenic cord divides into:
pronephros, mesonephros,metanephros
Pronephros
-appears at the 4th week
-degenerates by end of week 4
-has a pronephric duct and nephrotome
-first system that appears
-does not play any major role in kidney formation
Mesonephros
-appears between 4-6 weeks
-develop capillary system
-starts filtration of the kidney
-contains mesonephric ducts
Metanephros
-around 12 weeks
-kidney functions normally
Structure that gives the indication for the formation of the urinary system
Pronephros
Structure that appears at the beginning of the 4th week and disappears by the end of the 4th week …
Pronephros
Structure that appears in the early weeks of 4week after pronephros has disappeared…
Mesonephros
Structure where the first excretory tubules appear and form the S-Shaped Loop…
Mesonephros
Structure that acquires a collection of capillaries…
Mesonephros
Capillaries form glomerulus and around the glomerulus the tubules form…
Bowmans capsule
Glomerulus + Bowmans capsule form…
Renal Corpuscle
Structure that produces the excretion/reabsorption portion of the kidney but it is still not a functional kidney…
Mesonephros
Mesonephric or Wolffian Duct
tubule that enters collecting duct and has bowmans capsule, glomerulus and capillaries
In the middle of the second month, mesonephros forms a large ovoid organ on each side of the midline
thus developing…
Gonads
Ridges formed by mesonephros that help in the developing of the gonads is …
Urogenital ridges
Structure that develops the complete kidney and appears at week 5…
Metanephros
Metanephros is also known as the…
Permanent kidney
Structure appears at week 5 and is completely functional at week 12…
Metanephros
Metanephros contains 2 types of systems:
Collecting system and excretory system
Collecting system (from metanephros)…
-develops from the ureteric bud
-its an outgrowth of the mesonephric duct close to the cloaca
-penetrates the metanephric tissue
Excretory system(from metanephros)…
-S shaped tubules(collecting tubules) + renal vesicle (glomeruli) = excretory system or nephrons
Continous lenghtening of the excretory tubule results in formation of the …
Proximal convoluted tubule, Loop of Henle, Distal convoluted tubule
Which position is better to put kidney in a kidney transplant?
Left Side, because body has some kind of recollection of when kidney was first developed
Blood stream enters kidneys through…
Afferent and efferent arterioles
Metanephric mesoderm provides…
excretory units
Ureteric bud gives rise to…
Collecting system
Differentiation of the kidney involves Epithelial-Mesenchymal interaction… so it involves interaction between?
Epithelium of uteric bud(From mesonephros)
+
Mesenchyme (From metanephros blastema)
Mesenchyme (from Metanephros) expresses, what transcriptional factor?
WT1
WT1…
Regulates production of glial derived neurotrophic factor(GDNF) and hepatocyte growth factor (HGF) by the mesenchyme
thus stimulating …
branching and growth of the ureteric buds
also… makes the
Mesenchyme (from Metanephros blastema) competent to respond to the induction by the uteric bud
Epithelium of the uteric buds synthesize… Tyrosine Kinase Receptors
RET for GDNF
MET for HGF
Uteric buds induce mesenchyme via …
Fibroblast growth factor (FGF2) and Bone morphogenic protein 7 (BMP7)
FGF2 and BMP7 block…
Apoptosis and stimulate proliferation in metanephric mesenchyme while maintaining production of WT1
Uteric buds also express WNT9B and WNT6 which upregulate…
PAX2 and WNT4 in metanephric mesenchyme
WNT9B and WNT6 mediates conversion of mesenchyme to ….
epithelium for nephron formation
Anomalies in Number…
Renal agenesis= uteric bud fails to contact metanephric mesoderm (doesnt generate kidney)
Duplications= ureteric bud splits early before reaching metanephric mesoderm(Born eith 3 kidneys)
Ectopic ureters=two ureteric buds arise from mesonephric duct (1 kidney with 2 ureters, prone to having stones)
Anomalies in Kidney Ascent…
can be seen through ultrasound before birth and is related to females with turner syndrome
When kidney fails to ascend properly and its location become ectopic.
Horseshoe kidney
when inferior poles of the kidney fuse together and ascent is stopped by inferior mesenteric artery
Kidney can also fuse to the contralateral pole and ascend to the opposite side, which results…
in a cross-fused ectopy
Anomalies in Position..
Mal rotated kidney
Calyces can face anteriorly instead of posteriorly which causes…
obstruction of urine passing through
thus causes.. inadequate drainage leading to infection or stone formation
Polycystic Kidneys…
parenchyma of the kidney covered in cysts
Wilms tumor
Tumor in lower end of kidney ans is the #1 kidney tumor in children
Bladder and urethra forms during…
4th and 7th week
Cloaca divides into …
urogenital sinus(anteriorly) and anal canal(posteriorly)
Cloaca divides into urogenital sinus and anal canal through…
urorectal septum
If urorectal septum doesn’t completely separate urogenital sinus and anal canal, it leads to…
Fistula
Urogenital sinus divides into…
Bladder
Pelvic part= gives rise to the prostatic and membranous parts of urethra (prostate gland is produced)
Phallic part
In Males urogenital sinus divides into…
upper portion= becomes bladder
middle portion=becomes prostate and prostatic urethra
phallic portion=becomes penile urethra
In Females urogenital sinus divides into…
upper portion= becomes bladder
middle portion=becomes inferior vagina
phallic portion=connects with paramesonephric ducts
