2. Renal embryology (Kidney, Bladder, Suprarenal Gland)

Question 1

What is the first structure to produce urine in an early fetus?

Answer 1

The mesonephros

Question 2

From where is the collecting duct derived?

Answer 2

The collecting duct is derived from the ureteric bud.

Question 3

Why does a fetus need to have a well-developed suprarenal gland?

Answer 3

Because of the requirement of DHEA to continue the pregnancy

Question 4

What gives rise to the ureteric bud?

Answer 4

The caudal end of the mesonephric duct

Question 5

What gives rise to the trigone?

Answer 5

The mesonephric duct growing downwards

Question 6

What gives rise to the ureter, renal pelvis, and major and minor calyxes?

Answer 6

The ureteric bud

Question 7

When do we see the appearance of the pronephros?

When do we see it degenerate?

Answer 7

Early week four

It degenerates by day 24 or 25

Question 8

When do we expect to see the mesonephros producing urine?

Answer 8

From weeks 6 to 10

Question 9

From where is the nephron derived?

Answer 9

The nephron is derived from the metanephrogenic blastema, which forms metanephric tubules, which become the nephron.

Question 10

What gives rise to Bowman’s capsule?

Answer 10

The metanephric blastema

Question 11

What is the pathway of structures leading to the formation of what will become the adult kidney?

(Hint: 5 structures)

Answer 11

Urogenital ridge
Nephrogenic cord
Pronephros
Mesonephros
Metanephros

Question 13

What is derived from the pelvic part of the urogenital sinus?

Answer 13

The neck of the bladder, as well as:
in males, the prostatic urethra
in females, the entire urethra

Question 14

What gives rise to the cortex of the suprarenal glands?

Answer 14

Epithelial cells from the intraembryonic coelom

Question 15

What gives rise to the suprarenal medulla?

Answer 15

Neural crest cells

Question 16

What forms the efferent ductules in men?

Answer 16

The mesonephric tubules, which produce some urine in early fetal life

Question 17

What does the intermediate mesoderm form?

Answer 17

kidney and gonads

starts lateral to each somite and forms cylindrical structures

urinary system forms first

Question 18

First thing to form from the intermediate mesoderm is what?

What does the urogenital ridge form?

Answer 18

urogenital ridge which is a longitudinal band of mesoderm on each side of the dorsal aorta

nephrogenic cord which makes the nephric structures:

• pronephros
• mesonephros
• metanephros

Question 19

What is the order and function of the nephric structures?

Answer 19

pronephros (rudimentary)

mesonephros (functions in early fetal life)

metanephros (permanent kidneys)

Question 20

Pronephros appears when?

Pronephros degenerates when?

What does the pronephric duct do?

Answer 20

bilaterally early in 4th week in cervical region

by day 24-25

run caudally and open into cloaca and persist after pronephros degrades to be used by mesonephros

Question 21

When does the mesonephros appear?

What are the components of the mesonephros?

Answer 21

bilaterally in late 4th week caudal to pronephros

mesonephric ducts and tubules (ducts develop 1st and induce tubules from intermediate mesoderm)

Question 22

The mesonphric tubules form renal corpuscles which have two components:

Answer 22

1. medial end of tubules is cup shaped, glomerular capsule
2. tubule wraps around glomerulus (knot of capillaries)

Question 23

When are the mesonephric tubules functioning?

Answer 23

act as intermittent kidneys from 6-10 weeks, producing small amounts of urine

stop working after ten weeks and will regress in females

form efferent ductules in males

degenerate by 12wks

Question 24

The metanephros arises when?

Answer 24

during the 5th week, the ureteric bud is induced by the caudal end of each mesonephric duct

the metanephros consists of the ureteric bud and the blastema

Question 25

What is the ureteric bud? What is the metanephric blastema? When do these form a functional and definitive kindey?

Answer 25

outgrowth of mesonephric duct form nephrogenic cord 9-10th week *will have excretory and collecting portions*

Question 26

How does the ureteric bud morph into the collecting system?

Answer 26

ureteric bud elongates and penetrates the blastema to form the renal pelvis the stalk of the ureteric bud becomes the ureter cranial part of the ureteric bud branches into collecting tubules to first make the major calices and then the minor calices

Question 27

What are the five steps of nephron development?

Answer 27

1. collecting tubules induce **metanephrogenic** **blastema** to form **metanephric vesicles** 2. Metanephric vesicle will elongate to form **metanephric tubules** 3. proxomal end of tubules will form **glomerular capsule** and is invaded by glomeruli 4. distal end of tubule will lengthen and differentiate **into PCT, DCT, and nephron loop** 5. Each **DCT contacts an arched collecting tubule** and is now connected!

Question 28

Explain the blood supply to the kidneys

Answer 28

Kidneys start in pelvis and move up into abdomen first branch form from **common iliacs** (will undergo involution and disappear) definitive renal arteries are from **abdomdinal aorta**

Question 29

Unilateral renal agenesis

Answer 29

1:1000, males more affected typically asymptomatic suspected in infants with 1 umbilical A.

Question 30

bilateral renal agenesis

Answer 30

1: 3000 oligohydramnios non-viable, pulmonary hypoplasia, potter's sequence

Question 31

Renal Duplications

Answer 31

abnormal division of ureteric bud incomplete: divided/bifed kidney complete: double kidney and bifid ureter or separate ureters

Question 32

Horseshoe Kidney

Answer 32

1:1000 fusion of inferior poles asymptomatic ascent prevented by IMA (what is IMA)

Question 33

Accessory Renal Vessels

Answer 33

multiple renal arteries (2-4) 25% of adult kidneys affected 2x common as accessory veins can obstruct ureter and cause hydronephrosis "end arteries" so if damaged can cause ischemia

Question 34

Polycystic Kidney Disease

Answer 34

Autosomal recessive mutation in PKHD1 cysts present in both kidneys renal insuffiency 25% assx with pulmonary hypoplasia

Question 35

Multicystic dysplastic kidney disease

Answer 35

abnormal development of renal system cysts are probably dilations in loop of henle one kidney affected 75% of the time

Question 36

How is the urogenital sinus formed (the pee hole)

Answer 36

ventral cloaca contains the urogenital sinus and anorectal canal separated by the urorectal septum 1. vesicle part: forms most of bladder 2. pelvic part: forms neck of bladder, prostatic urethra (m) and urethra (f) 3. phallic part: spongy urethra (m), lining of vagina (f)

Question 37

How is the trigone formed?

Answer 37

at 4-6 weeks, mesonephric duct is incorporated into posterior wall of bladder ureteric bud is attached then and will connect openings of ureteric buds into bladder wall openings of mesonephric duct are carried inferiorly to the pelvic urethra this forms the trigone

Question 38

What is the trigone?

Answer 38

triangular region of the mesonephric and ureteric ducts blending into posterior bladder

Question 39

What develops from the vesicle part of the urogenital sinus? epithelium comes from submucosa nad muscularis comes from tigone comes from

Answer 39

bladder! urogenital sinus splanchnic mesoderm intermediate mesoderm

Question 40

the bladder is continuous with what structure? what forms the median umbilical ligament?

Answer 40

Allantois allantois constricts and forms the urachus extends from the apex of the bladder to the umbilicus this forms the median umbilical ligament

Question 41

Exstrophy of the bladder

Answer 41

1:10-40,000, typically males arises during body folding in 4th wk defective closure of ventral abdominal wall exposure of musosa of the posterior wall of the bladder

Question 42

Epispadias

Answer 42

1:30,000 males urethral opening is on the dorsum of the genital tubercle rather than on its ventral side Exostrophy of the bladder with epispadias occurs 1:40,000

Question 43

* Urachal cysts * Urachal sinus * Urachal fistula

Answer 43

* remnants of the epithelial lining of the urachus that can become enlarged and infected * end of the urachus remains open into bladder or umbilicus * entire urachus remains patent and allows urine to escape from umbilical orifice sx: leaking urine or other discharge, peritonitis, infection

Question 44

remeber the Zones and their hormones of the suprarenal gland? Medulla:

Answer 44

Salt, Sugar, Sex, the deeper you go the sweeter it gets. ZG: mineralcorticoids ZF: glucocorticoids ZR: sex hormones Medulla: chromaffin cells (Ne/Epi)

Question 45

What are the four steps in the development of the suprarenal glands?

Answer 45

1. 5ht week, coelomic epithelium delaminates and enters mesoderm making fetal cortical cells 2. ***_Neural Crest Cells_*** migrate into medulla and diff. into **chromaffin** cells. Contain **postganglionic** **sym****. neurons** (epi/ne) 3. Fetal cortex regresses and final cortical cells reorganize into the three zones 4. **fetal cortex secretes DHEA** and is converted to **estradiol** to maintain pregnancy, along with ACTH and glucocorticoids