Urinary System Embryo-cole Flashcards
The urinary and genital systems develop from what embryonic layer?
Intermediate mesoderm
Where is the intermediate mesoderm located initially?
Between the paraxial mesoderm (somites) and lateral mesoderm
At what point does the intermediate mesoderm separate from the lateral and paraxial mesoderm?
When the embryo undergoes lateral folding into a big tube
How do the developing kidneys end up on the posterior abdominal wall?
The embryo laterally folds into a big tube such that the neural tube, notochord, somites, and intermediate mesoderm all lie along the posterior aspect of the “tube”
After lateral folding of the embryo, what does the intermediate mesoderm form along the posterior aspect of the folded embryo?
Nephrogenic cord
Function of the nephrogenic cord
Sequentially segments from cranial to caudal into the 3 successive types of kidneys
Three types of kidneys stemming form the nephrogenic cord (intermediate mesoderm)?
Pronephros
Mesonephros
Metanephros
Where do the adult kidneys develop?
Why?
In the pelvis near the bladder
Come from the caudal region of the intermediate mesoderm (nephrogenic cord) at first
What structure runs alongside the nephrogenic cord (intermediate mesoderm) in the embryo?
Where is it derived from?
Mesonephric duct
Epithelium
What does the pronephros consist of following segmentation of the cervical nephrogenic cord?
When is the segmentation?
5-7 paired nephrotomes
4th week
What happens to the cervical nephrotomes (pronephros)?
Remain nonfunctional
Disappear around day 24-25
Describe formation of the mesonephros
In 4th week
About 40 mesonephric tubules form out of the nephrogenic cords in craniocaudal succession, then attach to the nephric duct
Where are the mesonephric ducts in relation to the mesonephric tubules?
When do they form?
Dorsolateral
At 24 days
What happens to the mesonephros?
Functional from weeks 6-10
Degenerate after week 10
Ducts used in males as ductus deferens (so NECESSARY for men)
Is the mesonephros used as anything in women?
Some vestigial structures
The region of the nephrogenic cord that eventually becomes the kidneys is initially called what?
This region is more formally called what?
Renogenic region
Metanephric blastema
First step of ureter formation
Metanephric blastema secretes GF’s that induce growth of the ureteric bud from the mesonephric duct
From what layer is the ureteric bud derived from?
Epithelium (from mesonephric duct)
What is required for the ureteric bud to communicate with the metanephric blastema (mesoderm)?
WT1 is expressed in mesoderm and must be turned on to receive signals from growing ureteric bud
What is a Wilms tumor?
Cause?
A kidney tumor caused by mutations in the WT1 gene. Causes poor communication between epithelium and mesoderm during kidney development
What is needed for the start of formation of the regions of the kidney?
Causes what?
PAX2 and WNT4 signaling from the ureteric bud
PAX2: Condensation of mesenchyme to prepare for tubule formation
WNT4: Mesenchyme epithelializes, getting ready for tubule system
What all is formed from the ureteric bud?
Embryonic layer?
Ureters, collecting ducts, major and minor calyces
Epithelium
What all is formed from the mesenchyme (mesoderm) of the metanephric blastema?
Renal corpuscle, PCT, loop, DCT