Embryology Flashcards
(35 cards)
What causes a Wilm’s tumor?
1.Cause: mutation of the WT1 gene which leads to abnormal differentiation of the intermediate mesoderm. Often presents with abnormalities of the reproductive system as well (due to the fact that the intermediate mesoderm gives rise to both the kidney and gonad).
At what age does a wilm’s tumor appear?
before age 5 typically
Most common malignant tumor in children
What arises from the nephrogenic ridge?
Urinary system
What arises from the gonadal ridge?
Reproductive system
The nephrogenic ridge and gonadal ridge are components of?
Intemediate mesoderm
What is the first set of kidneys that forms?
Pronephros (vestigial structure, forms during week 4)
What is the second set of kidneys? Are they functional?
Mesonephros - yes.
(form in month 3, drain to mesonephric duct (Wolffian)
Where does mesonephric duct drain to?
Cloaca
What is the “definative kidney”?
Metanephros
What are the two structures of the metanephros?
Metanephric blastema
Ureteric bud (metanephric diverticulum)
What forms the metanephric blastema? What excretory units does this form?
a. Forms from intermediate mesoderm within pelvis in a similar manner as mesonephros.
b. Forms excretory units of kidney (nephron)
1. Bowman’s capsule
2. Proximal convoluted tubules
3. Loops of henle
4. Distal convoluted tubules
What is the ureteric bud formed from? What does it penetrate? What components of the duct system does it form?
a. Evagination of mesonephric duct
b. Penetrates metanephric blastema.
c. Forms duct system
1. Collecting tubules
2. Minor and major calyces
3. Renal pelvis
4. Ureter
What causes renal agenesis?
a. Cause: Ureteric bud fails to form and/or induce differentiation of the metanephric blastema.
b. Can be unilateral or bilateral.
What arises in the case of bilateral renal agenesis?
Potter sequence
What does potter sequence result in? What secondary symptoms arise due to this?
Oligohydramnios (low levels of amniotic fluid)
Secondary symptoms caused by oligohydramnios…
- Hypoplastic lungs
- Potter facies: broad, flat nose; wide-set eyes; low-set ears; micrognathia.
- Sometimes limb malformation as well (club foot)
What is the cause of renal hypoplasia?
a.Cause: Inadequate branching of ureteric bud and lack of differentiation of nephrons.
What’s going on in renal hypoplasia? What is persistent fetal lobulation?
a. Functional nephrons are present, just very few.
b. Persistent fetal lobulation is a type of renal hypoplasia
What causes renal dysplasia?
Different causes, different types. Ex: multicystic dysplastic kidney - cystic diseases
What do we need to know about polycystic disease?
They are congenital
Describe the ascent of the kidneys
Week 6-9, normally kidney migrates out of pelvis into the abdomen. It rotates as it does so. As the kidney ascends it recieves new arteries. (initially from iliac arteries, post ascension, from aorta)
What causes horseshoe kidney?
Inferior poles of left and right kidneys fuse in pelvis. Ascent is blocked by inferior menteric artery.
What causes accessory renal arteries?
What are the symptoms?
a.Cause: Arise from persistence of caudal renal arteries during development.
Usually asymptomatic, in some cases can compress ureter and cause hydronephrosis
Can you just remove accessory renal arteries?
No, since they are segmental arteries (providing blood to an entire kidney segment.
What causes duplication of the urethra?
Splitting of the ureteric bud (should not happen)
