Renal Embryology

Question 1

3 embryonic germ cell layers

Answer 1

ectoderm
mesoderm
endoderm

Question 2

Mesenchyme

Answer 2

Loosely organized embryonic connective tissue (primarily derived from mesoderm, but sometimes also from other layers)

Question 3

The urogenitl system develops from…, specifically

Answer 3

intermediate mesoderm
specifically mesenchymal cells

Question 4

During lateral (transverse) folding, the intermediate mesenchyme is pulled ventrally forming…

Answer 4

two urogenital ridges (on the dorsal body wall)

Question 5

Each urogenital risge gives rise to…

Answer 5

nephrogenic cord and ridge, which form the urinary system

Question 6

3 sets of successive kidneys form from the nephrogenic cord in the craniocaudal axis, called…

Answer 6

pronephros
mesonephros
metanephros

Question 7

From the pronephros to the cloaca (causal end of gut tube), what will form?

Answer 7

Longitudinal nephric ducts

Question 8

Pronephros are rudimentary, transient structures that develop bilaterally at…

Answer 8

the 5th-7th cervical segments

Question 9

Two components of pronephros

Answer 9

• several paired clusters of cells (in lower cervical segments)
• pronephric ducts (paired tubular structures that extend caudally to the cloaca)

Question 10

What happens to the cranial parts of pronephric ducts?

Answer 10

They degrade (cuadal parts persist)

Question 11

Caudal pronephric ducts transition into…

Answer 11

mesonephric duct

Question 12

Caudal growth of pronephric/mesonephric ducts induces formation of…

Answer 12

mesonephric buds

Question 13

Mesonephric tubules within the mesonephric buds connect with…

Answer 13

mesonephric duct

Question 14

What are mesonephroi?

Answer 14

They function as interim kidneys in humans for ~4 weeks before the definitive kidneys (i.e. metanephroi) develop

Question 15

What do we call the “definitive” kidneys?

Answer 15

metanephroi

Question 16

Renal corpuscles form from…

Answer 16

mesonephric tubules

Question 17

Glomerular (Bowman’s) capsule forms at the…

Answer 17

medial end of the mesonephric tubule

Question 18

Glomerulus forms from…

Answer 18

the developing aorta

Question 19

Mesonephric ducts do not degenerate in everyone. Who keeps their mesonephric ducts?

Answer 19

Mesonephric ducts degenerate in females, but persist in males!

Question 20

What are the primordia of permanent, definitive kidneys?

Answer 20

Metanephroi

Question 21

Metanephroi begin developing around… and begin functioning around…

Answer 21

Metanephroi begin developing around week 5 and begin functioning around week 9

Question 22

Two functional components of metanephroi

Answer 22

1. Collecting portion: ureteric bud
2. Excretory portion: metanephrogenic blastema

Question 23

What is the ureteric bud?

Answer 23

Outgrowth from mesonephric duct near caudal end (sacral region)

Question 24

What is the metanephrogenic blastema?

Question 25

The ureteric bud stalk will become...

Answer 25

the ureter

Question 26

Generations of repetitive branching in the ureteric bud forms different components of mature kidneys.

Answer 26

First 4 generations: major calyces Second 4 generations: minor calyces 11 additional generations: system of collecting ducts

Question 27

What is reciprocal induction?

Answer 27

Interactions between ureteric bud and metanephrogenic blastema, each one inciting the other to grow. They signal to each other reciprocally.

Question 28

What is WT1

Answer 28

Transcription factor expressed in metanephrogenic blastema. Involved in the induction of ureteric bud growth

Question 29

What is GDNF?

Answer 29

Glial-derived neurotropic factor (GDNF) is a signalling molecule. Expressed in metanephrogenic blastema. Regulated by Pax2.

Question 30

Uriniferous tubules form fro two embryologically different components:

Answer 30

nephron: metanephrogenic blastema collecting tubules/duct: ureteric bud

Question 31

Describe the formation of the mesenchymal cap (3 steps)

Question 32

What is Potter syndrome?

Answer 32

Bilateral kidney agenesis. Can be caused by RET gene mutation.

Question 33

What are the consequences of Potter syndrome?

Answer 33

Absence of kidneys leads to decreased urine production and therefore oligohydraminos (low amniotic fluid levels). This leads to...?

Question 34

What is polycystic kidney disease?

Answer 34

Autosomal dominant polycystic kidney disease is one of the most common hereditary diseases linked to mutations in POLYCYSTIN genes (PKD1 & PKD2)

Question 35

What is another name for nephroblastmas?

Answer 35

Wilm's tumours

Question 36

What are nephroblastomas/Wilm's tumours?

Answer 36

?

Question 37

How do developed kidneys move from the pelvis, where they developed, to the ?

Answer 37

The relative ascent of the kidneys is attributed to the growth of the caudal end of the embryo.

Question 38

While kidneys "ascend", what else happens?

Answer 38

1. The kidneys rotate by 90deg so that the hilum faces medially in mature individuals. 2. Origins of renal blood changes & previos branches degrade...?

Question 39

What are horseshoe kidneys?

Answer 39

Atypical rotation and ascension of the kidneys associated with renal pole fusion (usually inferior poles).

Question 40

What is the nae of a rare variant of horseshoe kidneys?

Answer 40

Sigmoid kidney (inferior pole of one kidney fuses with the superior pole of the other).

Question 41

What are the symptoms of horseshoes kidneys?

Answer 41

Typically asymptomatic

Question 42

Horseshoe kidneys are prone tocomplications because of poor drainage. Examples include...

Answer 42

hydronephrosis ??

Question 43

What are the 2 main types of urinary tract duplication?

Answer 43

1. Incomplete division: divided kidney with a bifid ureter 2. Complete division: double kidney with a bifid ureter

Question 44

Urinary tract duplications result from...

Answer 44

abnormal divisions of the ureteric bud

Question 45

What is an example of ectopic kidney?

Answer 45

Pelvic kidney

Question 46

What is an ectopic kidney?

Answer 46

???

Question 47

What is the cloaca?

Answer 47

It is a common outlet at the caudal end of the developing embryo

Question 48

What are the 3 parts of the urogenital sinus?

Answer 48

1. Vesical part 2. Pelvic part 3. Phallic part

Question 49

Partitioning (septation) of the cloaca involves the formation of...

Answer 49

the urorectal septum

Question 50

Name 2 types of urachal anomalies

Answer 50

Urachal cysts Urachal fistula

Question 51

what is the urachus?

Question 52

Briefly describe the formation of ureters.

Question 53

What forms the trigone of the bladder?

Answer 53

The expanded flattened regions of mesonephric ducts

Question 54

Our bladder (inside) comes from 2 different germ layers...

Answer 54

endoderm mesoderm

Question 55

Suprarenal (adrenal) glands arise from 2 components:

Answer 55

- mesodermal mesenchyme - neural crest cells (ectoderm)

Question 56

The cortex of adrenal glands forms from...

Answer 56

mesodermal mesenchyme

Question 57

The medulla of the adrenal glands forms from...

Answer 57

neural crest cells (ectoderm)

Question 58

The cortex begins as an aggregation of mesenchymal cells. Two waves of these cells "delaminate" from the coelomic epithelium, forming...

Answer 58

The mesenchymal cells delaminate to form the fetal cortex (mostly regresses), followed by the adult cortex.

Question 59

The medulla of the adrenal glands is formed by migrating...

Answer 59

neural crest cells

Question 60

Neural crest cells that form the medulla of the adrenal glands differentiate into...

Answer 60

chromaffin cells