Embryology Of Urinary System

Question 1

What are the 3 developmental stages of the kidneys?

Answer 1

Pronephric
Mesonephric
Metanephric

Question 2

When is the primordium of the gut formed?

Answer 2

During embryological folding

Endoderm lined tube suspended within a cavity

Question 3

Name the 2 areas that have no mesoderm after gastrulation

Answer 3

Buccopharyngeal membrane (cranial) 
Cloacal membrane (caudal)

Question 4

How do areas with no mesoderm become openings?

Answer 4

No mesoderm therefore no blood vessels

The avascular tissue dies to create an opening

Question 5

Describe the pronephros

Answer 5

Appears in the cervical region (head and neck region)
Creates the pronephric duct which extends from the cervical region to the cloaca
Drives the development of the next stage

Question 6

Describe the mesonephros

Answer 6

The stage that takes over from the pronephros
Occupies a trench within the entire trunk of the embryo
Takes over the use of the duct

Question 7

Describe the metanephros

Answer 7

The true kidney

Appears in the pelvic region

Question 8

What is a nephrotome?

Answer 8

A primitive/prototype nephron

Question 9

What is the urogenital ridge?

Answer 9

Region of the intermediate mesoderm giving rise to both the embryonic kidney and the gonad

Question 10

Where does the ureteric bud sprout from?

Answer 10

Mesonephric duct

Question 11

What is the role of the ureteric bud?

Answer 11

Development of the ureters
Induces development in caudal region on the embryo
Releases signals to the intermediate mesoderm

Question 12

How can accessory renal arteries form?

Answer 12

As the kidneys move they sprout new vessels from the abdominal aorta. Usually the old vessels regress but if not then you get accessory vessels.

Question 13

Splitting of the ureteric bud can lead to:

Answer 13

Another lobe of the kidney formed
2 kidneys on one side
Extra ureters (lead to ectopic ureteral openings)

Question 14

What is the cloaca?

Answer 14

Where the GI, urinary and reproductive tracts all end early in development

Question 15

What is the urogenital sinus?

Answer 15

Created from the hindgut by the formation of the urorectal septum (wedge of mesoderm that grows down)
Separates the urinary and GI tracts
Continuous with the umbilicus via the urachus
Divided into 3 sections

Question 16

What are the 3 sections of the urogenital sinus called?

Answer 16

Upper (-> bladder)
Pelvic (-> urethra)
Phallic

Question 17

What is the adult derivative of the urachus?

Answer 17

Median umbilical ligament

Question 18

Males retain which duct to form the vas deferens?

Answer 18

Mesonephric duct

Question 19

Name the parts of the male urethra

Answer 19

4 parts:
Pre-prostatic
Prostatic 
Membranous (above 3 = pelvic part of UGS)
Spongy (phallic part of UGS)

Question 20

How does the spongy urethra form in men?

Answer 20

Genital tubercle elongate and genital folds fuse to form the spongy urethra
Driven by male sex hormones

Question 21

Where does the urethra open in the female?

Answer 21

Vestibule

Question 22

What is hypospadias?

Answer 22

Defect in the fusion of urethral folds

Urethra opens onto ventral surface of penis rather than at the end of the glans