Embryology

Question 1

Which layer of mesoderm becomes the kidneys and reproductive system (urogenital system)

Answer 1

Intermediate plate mesoderm

Question 2

What does the cloaca divide to form?

Answer 2

Rectum (GI tract) and anteriorly the Urogenital Sinus.

Question 3

What drains into the urogenital sinus?

Answer 3

Mesonephric duct

Question 4

What does the urogenital sinus later form?

Answer 4

The urinary bladder and its caudal end forms the urethra

Question 5

How many sets of kidneys develop sequentially during nephrogenesis?

Answer 5

3

Question 6

In which week does the intermediate mesoderm become the pronephros?

Answer 6

week 4

Question 7

What is the Pronephros?

Answer 7

Made up of the pronephric duct + rudimentary pronephric tubules

First epithelial structure formed within the intermediate mesoderm

Question 8

What does the pronephric duct drain into?

Answer 8

The cloaca

Question 9

When do the pronephros degenerate (except the pronephric duct)?

Answer 9

Week 5

Question 10

What was the Mesonephric duct originally?

Answer 10

The pronephric duct

Question 11

What is the mesonephros and what does it function as for approx 4 weeks?

Answer 11

It is Intermediate mesoderm in trunk region, late Week 4.

Functions as the kidney

Question 12

When do the metanephros start to develop and when do they then start to function?

Answer 12

Develop at bout week 5

start to function around week 9

Question 13

What does the metanephros consist of? (2)

Answer 13

A ureteric bud that develops off the mesonephric duct

Metanephric mesoderm (the most caudal part of the intermediate mesoderm)

Question 14

What happens to the mesonephros?

Answer 14

Most will be incorporated into the developing gonad

Question 15

What do the mesonephric tubules become?

Answer 15

The rete testis

Question 16

What does the mesonpheric duct become?

Answer 16

Vas deferens

Question 17

What happens to the mesenephros and mesonephric duct in females?

Answer 17

The mesnephros becomes the ovary but the tubules and mesonephric duct degenerate

Question 18

The ureteric bud undergoes repeated branching at its distal end. What does it become?

Answer 18

The stalk becomes the ureter and the expanded cranial end becomes the renal pelvis.

Question 19

What do the first 4 generations of branches from the ureteric bud become?

Answer 19

They merge to become the major calyces

Question 20

What do the next 4 generations of branches from the ureteric bud become? (after the first 4)

Answer 20

Minor calyces

Question 21

The remaining generations of branches formed from the ureteric bud become what?

Answer 21

Collecting tubules

Question 22

What does the nephron consist of?

Answer 22

Renal corpuscle + Proximal CT + Loop of Henle + Distal CT

Question 23

What does the Uriniferous tubule consist of?

Answer 23

Nephron and collecting duct

Question 24

What does the nephron develop from?

Answer 24

Metanephric mesoderm

Question 25

What do the Collecting duct and calyces, pelvis and ureter develop from?

Answer 25

Ureteric bud

Question 26

What level do the kidneys lie at

Answer 26

T12-L3

Question 27

When do the kidney’s stop ascending during development?

Answer 27

When they come into contact with the adrenal glands

Question 28

Allantois and cloaca form what?

Answer 28

The urinary bladder and urethra

Question 29

Summary

Answer 29

1. Allantois and cloaca => urinary bladder and urethra
2. Intermediate mesoderm develops into the rudimentary pronephros in neck (week 4), Mesonephros in trunk region (week 5 to 9) with a duct and tubules. Duct drains into cloaca
3. Ureteric bud grows out of the caudal end of the mesonephric duct…
4. . …and branches to form the renal pelvis, calyces and collecting duct
5. The ureteric bud and the metanephric mesoderm reciprocally induce each other

Question 30

What does the paraxial mesoderm form?

Answer 30

Somites

Question 31

What does the lateral plate mesoderm develop into?

Answer 31

Body cavity and coverings