Urinary System

Question 1

What are the four main components of the urinary system and from which germ layer does each derive?

Answer 1

Kidneys (mesoderm), Ureters (mesoderm), Urinary bladder (endoderm), Urethra (endoderm)

Question 2

Name the three kidney sets seen during development and when each appears

Answer 2

Pronephros (4th week, is vestigeal), Mesonephros (later in 4th week, is interim kidney), Metanephros (5th week, is true kidney)

Question 3

What does the mesonephros end up becoming in males?

Answer 3

Epididymis and vas deferens

Question 4

Give the relationships of the three primordial kidney systems

Answer 4

Pronephros rostral to mesonephros rostral to metanephros (i.e. pro is most rostral, meta is most caudal)

Question 5

What do the mesonephric ducts terminate into and what do they become in the adult?

Answer 5

Terminate into cloaca, become genital ducts in males

Question 6

What structures does the genital ridge develop into in males and females respectively, and how far into development is this ridge the same in the two sexes?

Answer 6

Testes in men, ovaries in women. Ridge is same in both until week 6

Question 7

What are the two developmental sources of the metanephroi (permanent kidneys) and what is the function of each?

Answer 7

Ureteric bud (collection) and Metanephric blastema (urine production)

Question 8

The ureteric bud is an outgrowth of what structure and initially connects what to what?

Answer 8

Outgrowth of mesonephric duct, initially connects metanephric blastema to cloaca

Question 9

How do the ureteric bud and metanephric blastema influence each other developmentally?

Answer 9

Through reciprocal induction (they induce each other to develop into the correct structure)

Question 10

What cell signaling factor is important in reciprocal signaling in the developing kidney, what condition to this lead to, and how does it present?

Answer 10

WT1, Wilms tumor (of the kidney), presents as mass over kidney region

Question 11

Give the levels of the kidney collecting system in order

Answer 11

Collecting tubules, Minor calyx, Major Calyx, Renal pelvis

Question 12

Name the parts of the nephron in order and what they are derived from

Answer 12

Renal corpuscle (consists of glomerulus and bowmans capsule), Proximal Convoluted Tubule, Loop of Henle, Distal Convoluted Tubule. They are derived from metanephric blastema

Question 13

What is the function of the prenatal kidney?

Answer 13

Supplementing amniotic fluid. Urine production is not the primary function until after birth

Question 14

Describe the positional change that occurs for the kidneys, mesonephrons and gonads during development

Answer 14

The mesonephros/gonads descend (along with the rest of the body) and the kidneys ascend along the posterior abdominal wall

Question 15

What happens to the kidneys and their arterial supply as the ascend during development?

Answer 15

They rotate medially, new arterial supplies are formed and old ones degenerate

Question 16

What are pelvic and horseshoe kidneys and why do they occur?

Answer 16

One (pelvic) or both (horseshoe) kidneys remaining in the pelvic area. Caused by a failure of the kidneys to ascend and medially rotate during development (weeks 6-9)

Question 17

What does the cloaca become?

Answer 17

The urogenital sinus (which becomes bladder and uretrha) and rectum

Question 18

Urinary trigone

Answer 18

A patch of mesoderm integrated into the bladder wall where it meets the ureter

Question 19

What is the origin of the epithelium, and inner wall muscle respectively, in the bladder?

Answer 19

Epithelium on inner surface is endodermal, muscle is mesodermal

Question 20

What is the median umbilical ligament a derivative of?

Answer 20

The urachus, which is a fibrous cord that is remnant of the allantois

Question 21

The trigone of the bladder is formed as what two structures intercalcate into the bladder?

Answer 21

The ureteric bud (becoming the ureter) and the mesonephric duct)

Question 22

What might cause leakage of urine between the bladder and the umbilicus?

Answer 22

A patent urachus (fistula) with a urachal sinus. A remaining urachus would connect the bladder to the umbilicus