Embryology - Renal Flashcards
From what embryological layer is the urogenital system derived?
Intermediate Plate Mesoderm
What embryonic layer forms the peritoneum?
- Lateral plate mesoderm splanchnic layer = Visceral
- Somatic layer = Parietal
What is the allantois?
- An outpouching of endoderm at the hindgut that extends into the body stalk (body stalk eventually becomes umbilical cord)
- It connects to the cloaca
What is the cloaca?
- Caudal end of endoderm
- It is divided into the urogenital sinus and rectum by a growth of mesoderm (Urorectal Sectum)
Quick summary of kidney development?
- Develops segmentally:
- Pronephros in early week 4
- Mesonephros by week 5
- Metanephros take over in week 9
Where in the embryo does the pronephros form?
Neck
What makes up the pronephros and what happens to it?
- Pronephric duct (drains into cloaca)
- Rudimentary Pronephric tubules
- The tubules degenerate by week 5 but the duct remains
Where in the body does the mesonephros form?
Trunk region late in week 4/early week 5
What makes up the mesonephros?
- The mesonephric duct, develops from the pronephric duct and still drains into the cloaca
- Mesonephric tubules (Drain into the duct)
What happens to mesonephros after the metanephros takes over?
Mesonephric tubules ⇒ Rete Testis
Mesonephric Duct ⇒ Vas Deferens
In women they mostly degenerate and the remainder becomes ovaries. Undifferentiated cells from the yolk sac migrate in and undergo spermatogonia and Oogonia
When/where does the metanephros develop?
- Starts at week 5 and takes over functioning at week 9
- Develops down on either side of the bladder
How does the metanephros develop?
- Ureteric bud grows out from mesonephric duct into surrounding metanephric mesoderm and continually branches to form the collecting system
- The stalk of the bud becomes the ureter and the expanded cranial end the renal pelvis
- The metanephric mesoderm becomes the kidney
What do the branches of the ureteric bud become?
- 1st 4 generations of branches ⇒ Major Calyces
- 2nd 4 generations of branches ⇒ Minor calyces
- Remaining gens become collecting tubules
What induces metanephros formation?
- The ureteric bud and metanephric mesoderm
- Reciprocally Induce eachother
When do nephrons develop?
Continuously to about week 32
