Embryology - Urinary System

Question 1

What does the paraxial mesoderm form?

Answer 1

Somites

Question 1

What does the intermediate plate mesoderm form?

Answer 1

Urogenital system (kidneys and repro.)

Question 2

What does the lateral plate mesoderm form?

Answer 2

Body cavity and coverings

Question 3

What is the position of the intermediate mesoderm?

Answer 3

Retroperitoneal position

Question 4

What is the allantois?

Answer 4

Outpouching of the endoderm at the hindgut that extends into body stalk

Question 5

What is the cloaca?

Answer 5

Single posterior opening at hindgut
In birds - for birds digestion, urinary and reproduction tracts are together

Question 6

What is the cloaca divided into?

Answer 6

Rectum posteriorly
Urogenital sinus anteriorly

Question 7

What separates the cloaca?

Answer 7

Urorectal septum

Question 8

What forms the urinary bladder?

Answer 8

Urogenital sinus

Question 9

What happens during the 4th week to the intermediate mesoderm?

Answer 9

In neck region becomes pronephros

Question 10

What is the pronephros?

Answer 10

Pronephric duct and rudimentary pronephric tubules
Pronephric duct drains into cloaca
Rudimentary kidneys

Question 11

When does the pronephros degenerate?

Answer 11

By 5th week except the pronephric duct

Question 12

What is the mesonephros?

Answer 12

Intermediate mesoderm in trunk region
Late in week 4
Pronephric duct becomes mesonephric duct
Mesonephric tubules develop and drain into mesonephric duct

Question 13

How long does the mesonephros function as the kidney?

Answer 13

Approx. 4 weeks

Question 14

When does the metanephros (definitive kidney) develop?

Answer 14

From about 5th week but starts to function around week 9

Question 15

What does the metanephros consist of?

Answer 15

A ureteric bud that comes off the mesonephric duct
Metanephric mesoderm - caudal part of intermediate mesoderm

Question 16

What happens to the mesonephros?

Answer 16

Much of it will be incorporates into developing gonad
Undifferentiated cells from yolk sac migrate in to form spermatogonia/ oogonia

Question 17

What does the mesonephric tubules and duct become?

Answer 17

Tubule - rete testis
Duct - vas deferens
In females - ovary but tubules and duct degenerate

Question 18

Describe the further development of the ureteric bud

Answer 18

Undergoes repeated branching at its distal end
Stalk becomes ureter and the expanded cranial end becomes the renal pelvis

Question 19

What does the 4 generations of branches of ureteric bud become?

Answer 19

First 4 become confluent to become major calyces
Next 4 form minor calyces
Remaining become the collecting tubules

Question 20

What forms the kidneys?

Answer 20

Metanephric membrane from the intermediate plate mesoderm

Question 21

What does the nephron consist of?

Answer 21

Renal corpuscle + PCT + loop of Henle + DCT

Question 22

What does the uriniferous tubule consist of?

Answer 22

Nephron + collecting duct

Question 23

What develops from the ureteric bud?

Answer 23

Collecting duct and calyces, pelvis and ureter

Question 24

Describe the ascent of the kidneys

Answer 24

Initially lie on either side of bladder and in developing pelvis
Kidneys come to lie in upper abdomen - T1-L3
Hilum rotates ventral to medial
Stops when come in contact with adrenal glands
Differential growth of lower body inferiorly away from kidneys

Question 25

What is the relationship between the ureteric bud and metanephric mesoderm?

Answer 25

Reciprocally induce each other