Embryology of the Urinary System

Question 1

Which part of the mesoderm does the urinary system develop from?

Answer 1

Intermediate plate mesoderm

Question 2

What is the allantois?

Answer 2

The outpouching of endoderm at the hindgut that extends into the body stalk

Question 3

What is the cloaca?

Answer 3

The single posterior opening for the birds digestive, urinary and reproductive tracts: used to expel faeces and lay eggs

Question 4

What structures are formed when the cloaca divide?

Answer 4

Rectum and urogenital sinus

Question 5

Which duct drains into theurogenital sinus?

Answer 5

Mesonephric

Question 6

What does the urogenital sinus develop into?

Answer 6

The bladder (the caudal end also does forms the urethra

Question 7

What happens to the intermediate mesoderm in the neck during week 4?

Answer 7

It forms the pronephros

Question 8

What structures make up the pronephros?

Answer 8

Pronephric duct + rudimentary pronephric tubules

Question 9

Where does the pronephric duct drain?

Answer 9

The cloaca

Question 10

What happens to the pronephros in humans?

Answer 10

The pronephros mainly degenerates by week 5 except the pronephric duct

Question 11

What are the mesonephros?

Answer 11

Intermediate mesoderm in the trunk (late week 4)

Question 12

What happens to the pronephric duct?

Answer 12

It becomes the mesonephric duct

Question 13

What structures drain into the mesonephric duct?

Answer 13

Mesonephric duct

Question 14

What is the function of the mesonephros?

Answer 14

They function as kidneys for approx. 4 weeks

Question 15

What are the metanephros?

Answer 15

The definitive kidneys

Question 16

At what point do the metanephros develop and when do they start to function?

Answer 16

Develop Begins: Week 5

Function: Week 9

Question 17

What do the metanephros consist of?

Answer 17

A ureteric bud (develops off the mesonephric duct) and the metanephric mesoderm

Question 18

What happens to the mesonephros?

Answer 18

Most of the mesonephros will be incorporated into the developing gonad

Question 19

What happens to the mesonephric tubules?

Answer 19

It becomes Rete testis

Question 20

What happens to the mesonephric duct?

Answer 20

It becomes the vas deferens

Question 21

What happens to the mesonephric tubules and duct in females?

Answer 21

They degenerate

Question 22

How does the ureteric bud further develop?

Answer 22

It repeatedly branches at its distal end

Question 23

What structures do the stalk and the expanded cranial end of the ureteric bud form?

Answer 23

Stalk: ureter

Expanded cranial end: renal pelvis

Question 24

What do the first four generations of branches of the ureteric bud form?

Answer 24

Major calyces

Question 25

What do the 2nd four generations of the branches of the ureteric bud form?

Answer 25

Minor calyces

Question 26

What do the remaining generations of the ureteric bud branches form?

Answer 26

Collecting tubules

Question 27

Is a nephron and uriniferous tubule the same thing?

Answer 27

No Nephron = renal corpuscle + PCT + loop of henle + DCT Urniferous tubule = nephron + collecting duct

Question 28

Where do the kidneys initially lie?

Answer 28

On either side of the bladder

Question 29

What happens to the kidneys as the foetus develops?

Answer 29

They appear to ascend into the abdomen mainly due to the growth of the lower body away from the kidneys

Question 30

Where do the kidneys eventually end up?

Answer 30

Upper abdomen (T12-L3)

Question 31

What stops the ascent of the kidneys?

Answer 31

When they come into contact with the adrenal gland