Development of the kidney

Question 1

Timeline of the development of the

1. pronephros
2. mesonephros
3. metanephros

Answer 1

1. pronephros: 3-4 weeks
2. mesonephros: 4 weeks - 2 months
3. metanephros: 5 weeks-maturity

Question 2

1. pronephros
2. mesonephros
3. metanephros
   All of these develop initially from what?

Answer 2

Nephrogenic cord in the urogenital ridge

Question 3

The primordia begins as an undifferentiated group of mesodermal cells along the length of the nephrogenic cord, and first develops into what?

Answer 3

small groupings of cells or nephrotomes (w/in somites)

Question 4

Which direction do the nephrotomes become progressively less distinct?

Answer 4

anterior nephrotomes –> posterior less distinct

Question 5

How does the mesonephric duct form?

Answer 5

nephrotomes vesiculate and join → pronephric duct → more neprhotomes add to the duct → mesonephric duct

Question 6

How does the Wolffian duct form?

Answer 6

Mesonephric duct grows caudally to join with developing cloaca

(so this means that the mesonephric duct will eventually become part of the male reproductive system, and degen in females)
- also worth mentioning is that the paramesonephric duct also joines with cloaca

Question 7

How long does it take the pronephros to degenerate and disappear by?

Answer 7

4 weeks

Question 8

What becomes the Wolffian body?

Answer 8

further development of urogenital ridge

Question 9

Which duct forms the Oviduct and uterus?

Answer 9

The paramesonephric duct / Mullerian duct

- develops form an invagination of the coelom wall and runs along most of the Wolffian body to also join the cloaca

Question 10

What develops from the ureteric bud?

Answer 10

renal pelvis
major calyx
minor calyx
ureter
collecting duct/tubules

• note that the metanephric blastema envelopes the bud

Question 11

Malpighian pyramids

Answer 11

Series of outgrowths as tubules from ureteric bud run parallel to each other from medulla to cortical regions

• will become the collecting tubules.
• these will stop growing

Question 12

What happens when the tips of the collecting tubules (malpighian pyramids have become them)?

Answer 12

then the mesoderm that originated in metanephric blastema (remember that this enveloped the ureteric bud) starts to differentiate → metanephric spheroid → metanephric vesicle → metanephric tubule (rest of nephron)

Question 13

What gives rise to the bladder and urethra?

Answer 13

They develop from the urogenital sinus which originates from the caudal endoderm, cloaca.
The mesonephric duct joins the cloaca at the region that will become the urogenital sinus
- The trigone is actually made from mesoderm

(in males the mesonephric duct separates fully from insertion)