Lecture 2: Kidney, Bladder, and Suprarenal Gland Embryo Flashcards
3 separate kidneys develop, what are they called?
1) Pronephros
2) Mesonephros
3) Metanephros
In the Intermediate mesoderm, you have a structure in which the nephron and the duct system will form. What is this structure?
Nephrogenic cord
What embryological layer gives rise to the kidneys?
Intermediate mesoderm
What is the first kidney formed, when, and where in the body, when does it degenrate; is it functional?
Pronephros during the 4th week; forms in the neck/cervical region; degenerates late 4th week; never functional
What structures move down towards the cloaca in week 4?
Pronephric ducts
When does the Mesonephros appear and function; for how long is it functional?
Appears late in 4th week; serves as interim kidney for 1st trimester (urine production); functional until about 11 weeks.
Where does the Mesonephros form?
Thoracic and Lumbar region
What will the mesonephric tubule form?
Forms the actual nephronic unit that will concentrate urine.
When and where does the Metanephros form; significance?
Forms during 5th week in pelvic region and is the true kidney.
Where does the Metanephric duct come off of and eventually becomes?
Sprouts off the mesonephric duct (aka uteric bud) and eventually becomes the ureter
What is the embryological origin of the Glomeruli (capillaries), Bowman’s capsule, and Mesonephric tubules?
Glomeruli: Somatic lateral plate mesoderm; lateral segmental arteries
Bowman’s and Mesonephric tubules: Intermediate mesorderm
What induces nephrons to grow?
The mesonephric duct induces nephrons in adjacent nephrogenic cord to grow.
What is the major component of amniotic fluid?
Fetal urine
What 2 structures does the Metanephros give us and where are the derived from?
1) Uteric bud (metanephric duct): outgrowth from mesonephric duct
2) Metanephric blastema: derived from nephrogenic cord
What 5 structures form from the Uteric bud?
1) Ureter
2) Pelvis
3) Major calyces
4) Minor calyces
5) Collecting tubules
What 4 structures form from the Metanephric blastema?
1) Renal vesicles
2) Bowman’s capsule
3) Proximal and distal convoluted tubules
4) Loop of Henle
Describe the subsequent bifurcations in the development of the collecting system?
- Uteric bud first contacts metanephric blastema and will give rise to renal pelvis
- Uteric bud bifurcates and branches/come together to form major calyces
- Branches will branch again and then combine to form the minor calyces
Nephron originates where and is surrounding what?
As a vesicle within the blastemic cap surrounding the ampulla of a collecting duct
What happens to the vesicle within the blastemic cap?
Elongates into a tube and the glomerulus forms at one end, tubule near the glomerulus will invaginate and form Bowman’s capsule
What occurs at the other end of tubule formed from the blastemic cap?
Lengthens and differentiates into the proximal convolute tubule, loop of henle, and the distal convoluted tubule
Explain unilateral renal agenesis; more common in; Dx??
- Missing one kidney, affects males more than females, and typically the left kidney is missing.
- Asymptomatic
- Dx using US if you see ONE umbilical artery
Explain bilateral renal agenesis; associated with; Tx?.
No kidneys!
- Associated with oligohydramnios, because fetal urine is not being produced and is the major component of amniotic fluid
- These infants need dialysis and kidney transplant to survive
Embryologically how do we account for unilateral agenesis?
Ureteric bud did not form or it formed and then degenerated. Without ureteric bud we get no ureteric cord or mass.
What’s duplex kidney and how does it occur embryologically?
- Having 2 ureters
- Results from abnormal division of ureteric bud
Renal agenesis is commonly seen in which patients?
20% of Potter sequence patients
When do kidneys reach adult position and what occurs to get them there?
- By 9th week
- Ascent from caudal growth of embryo
- Rotate 90 degrees during ascent
Where do kidneys receive blood supply from during ascent; which arteries?
Vessels that are closest to them
- In pelvis: Common iliac arteries
During ascent: Renal arteries from aorta
What structure do the kidneys end their ascent by?
Suprarenal gland (aka adrenal glands)
Why does a pelvic kidney (eptopic) not ascend?
Lattice network of blood vessels can trap the kidney and stop it from ascending. Kidney will still be functional.
What’s a horseshoe kidney; can’t ascend why; stops at what level?
- The inferior poles of each kidney are fused together
- Runs into Inferior Messenteric a. during ascent and stops around L3
7% of individuals with Turner syndrome also have?
Horseshoe kidney
What 2 problems can occur from accessory renal vessels (“end” arteries)?
1) Can cross/compress the ureter
2) Are “end” arteries so they are the only blood supply to a tissue. If they are obstructed or ligated you get necrosis.
Discuss Autosomal Recessive Polycystic Kidney Disease.
Cause (genetically), what’s affected, associated with?
- Mutation of PKHD1 gene
- Both kidneys full of cysts
- Renal insufficiency
- 25% associated with pulmonary hypoplasia
Discuss Multicystic dysplastic kidney disease
Cause, what’s affected
- Usually only affects 75% of ONE kidney
- Fewer cysts
- Though that cysts are wide dilations of the Loop of Henle
From where is the Ureter derived from?
Mesonephric and Metanephric ducts
The bladder is derived from which ‘derm?
Hindgut endoderm (epithelial layer)
Trigone is derived from which ‘derm?
Intermediate mesoderm
The mesonephric duct gets incorporated where and becomes the?
Posterior bladder wall and forms the Trigone
The cloacal membrane gets contributions from which ‘derm layers?
Ectoderm and Endoderm
What derm layer is the Allantois from and what does it become?
- Hindgut endoerm
- Allantois –> Urachus –> Median Umbilical L.
The Urogenital Sinus is composed of what 3 regions?
1) Vesicle part: bladder
2) Pelvis Part
3) Phallic
What does the Pelvis part of urogenital sinus become in females vs. males?
Females: Urethra
Males: Prostatic and Mebranous urethra
What does the Phallic part of urogenital sinus become in females vs. males?
Females: Lining of the vestibule
Males: Spongy Urethra
The Urorectal septum separates what into what?
Separates cloacal membrane into:
- Urogenital membrane
- Anal membrane
What is a urachal fistula, symptoms?
- Bladder is connected to the belly button (aka umbilicus)
- Sx: Urine leaking out of belly button
What is a Urachal cyst?
- A cysts of the median umbilical lig., usually patients won’t know they have
What’s a Urachal sinus, what problems may arise?
- Not quite a fistula, but is a really deep opening (deep belly button)
- Men with prostate problems can sometimes have urinary retention which forces this open causing a urachal fistula
What is Exstrophy of the bladder (aka extopic vesicase)?
Arises when, caused by, what’s exposed?
- Arises during body folding (week 4)
- Defective closure of ventral abdominal wall
- Mucosa of posterior wall of bladder exposed
What is Exstrophy of the bladder highly associated with?
Episadias - opening on dorsal surface of penis
When Episadias occurs in isolation is a result of?
Improper location of genital tubercles caudal to cloacal membrane
What is a patent urachus, cause?
- Open channel between the bladder and the umbilicus (urachal fistula).
- Failure of the allantois to produce median umbilical ligament
What cells give rise to the medulla: chromaffin system?
Neural Crest Cells
What derm layers gives rise to the capsule?
Mesoneprhic mesoderm (intermediate mesoderm)
The cortex is comprised of what kind of epithelium from which derm layer?
Coelomic epithelium (somatic lateral plate mesoderm)
What causes the first and second cellular waves and what is created
Coelomic epithelium (somatic lateral plate mesoderm) creates:
First wave: Fetal cortex
Second wave: Adult cortex
Fetal cortex is important for producing?
- Pituitary ACTH
- Glucocorticoids
- Dihydroepiandrosterone (estrogen precursor)
What structure does the mesonephric duct form in adult?
Vas deferens - part of male genitalia
