Urinary Embryology

Question 1

From what embryological layer is the urogenital system derived?

Answer 1

Intermediate Plate Mesoderm

Question 2

What embryonic layer forms the peritoneum?

Answer 2

The lateral plate mesoderm splanchnic layer = visceral Somatic layer = Parietal

Question 3

What is the allantois?

Answer 3

An outpouching of endoderm at the hindgut that extends into the body stalk (body stalk eventually becomes umbilical cord) It connects to the cloaca

Question 4

What is the cloaca?

Answer 4

Caudal end of endoderm It is divided into the urogenital sinus and rectum by a growth of mesoderm (Urorectal Sectum)

Question 5

Quick summary of kidney development?

Answer 5

Develops segmentally: - Pronephros in early week 4 - Mesonephros by week 5 - Metanephros take over in week 9

Question 6

Where in the embryo does the pronephros form?

Answer 6

NEck

Question 7

What makes up the pronephros and what happens to it?

Answer 7

• Pronephric duct (drains into cloaca) - Rudimentary Pronephric tubules The tubules degenerate by week 5 but the duct remains

Question 8

Where in the body does the mesonephros form?

Answer 8

Trunk region late in week 4/early week 5

Question 9

What makes up the mesonephros?

Answer 9

The mesonephric duct, develops from the pronephric duct and still drains into the cloaca Mesonephric tubules (Drain into the duct)

Question 10

What happens to mesonephros after the metanephros takes over?

Answer 10

Mesonephric tubules -> Rete Testis Mesonephric Duct -> Vas Deferens In women they mostly degenerate and the remainder becomes ovaries. Undifferentiated cells from the yolk sac migrate in and undergo spermatogonia & Oogonia

Question 11

When/where does the metanephros develop?

Answer 11

Starts at week 5 and takes over functioning at week 9 Develops down on either side of the bladder

Question 12

How does the metanephros develop?

Answer 12

Ureteric bud grows out from mesonephric duct into surrounding metanephric mesoderm and continually branches to form the collecting system The stalk of the bud becomes the ureter and the expanded cranial end the renal pelvis The metanephric mesoderm becomes the kidney

Question 13

What do the branches of the ureteric bud become?

Answer 13

1st 4 generations of branches –> Major Calyces 2nd 4 generations of branches –> Minor calyces Remaining gens become collecting tubules

Question 14

What induces metanephros formation?

Answer 14

The ureteric bud and metanephric mesoderm Reciprocally Induce eachother

Question 15

When do nephrons develop?

Answer 15

Continuously to about week 32

Question 16

How do nephrons form?

Answer 16

Mesoderm converts to epithelium. Forming metanephric vesicles Vesicles form metanephric tubules Tubule & Collecting duct merge Glomerulus forms and invaginates the tubule Uriniferous tubule lenghtens

Question 17

Define Nephron

Answer 17

The renal corpuscle, loop of henle and proximal/distal collecting ducts

Question 18

Define uriniferous tubule?

Answer 18

The nephron and the collecting duct

Question 19

What structures develop from the ureteric bud?

Answer 19

Collecting duct Calcyces Pelvis Ureter

Question 20

How do the kidneys ascend from thier position by the bladder to their adult position?

Answer 20

Growth of lower body inferiorly away from them . not actual ascent

Question 21

What happens to the kidney orientation?

Answer 21

They rotate 90*. The hilum going from ventral to medial

Question 22

How does the kidney vasculature develop?

Answer 22

Its forms and regresses segmentally as the kidney ascends

Question 23

Heres some congenital abnormalities?

Answer 23

• Congenital Polycydstic Kidney Disease - Aberrant Renal Arts - Lobulated Kidney - Transposition of kidney - Horseshoe kidney - Pancake kidney

Question 24

What are aberrant renal arts?

Answer 24

Renal arteries enter the kidney not at the hilum

Question 25

What is a lobulated kidney?

Answer 25

Not a nice smooth shape, instead lots of sticking out lobes

Question 26

What is transposition of the kidney?

Answer 26

The kidney is on the wrong side, either: - Below the other one - Next to the other one - Swapped sides with the other one

Question 27

What is a horsheshoe and pancake kidney?

Answer 27

Horseshoe kidney - Fusion of the two kidneys at inf or sup pole Pancake kidney - fuses at both poles forming a pancake of kidney across the whole abdomen