Renal Embryology

Question 1

what embryonic cell type does the kydneys give rise from

Answer 1

Intermediate mesoderm

also will give rise to the gonads as well but the urinary system develops first

Question 2

where is the Intermediate mesoderm located on the trilaminar disk

Answer 2

found inbetween the paraxial mesoderm and the lateral plate mesoderm

Question 3

what structure does the urogenital system give rise from

Answer 3

the urogenital ridge: longitudinal band of mesoderm that forms on each side of the dorsal aorta

Question 4

what develops from the urogenital ridge and what structures does this give rise to

Answer 4

the urogenital ridge will give rise to the nephrogenic cord

this will give rise to the nephric structurues:

• pronephros
• mesonephros
• metanephros

Question 5

what is the development progression of the kidney

Answer 5

Urogenital ridge
Nephrogenic cord
Pronephros
mesonephros
metanephros

Question 6

Function and characteristics of the Pronephros

Answer 6

Bilateral transitory structures

• appear in 4th week
• Located in cervical region

Pronephric ducts run caudally and open into the cloaca

degenerate by 24-25 days

But pronephric ducts persist and are used by the mesonephros

important for the initiation of the cascade that leads to the formation of the definitive kidney

Question 7

Function and characteristics of the Mesonephros

Answer 7

Bilateral transient structures

• appear late 4th week
• caudal to pronephros

Includes the mesonephric ducts and tubules

• ducts develop 1st
• induce tubules from surrounding intermediate mesoderm

Question 8

what do the mesonephric tubules form? and how long do they function

Answer 8

form the renal corpuscles

• medial end of the tubules is a cup shaped, glomerular capsule
• wraps around the glomerulus

Function as the interm kidneys from 6-10 weeks and produce small amounts of urine

after 10weeks stops functioning:

• will regress in females
• will form efferent ductules in males
• Degenerate by 12 weeks

Question 9

what makes up the metanephros

Answer 9

Ureteric bud: outgrowth of mesonephric duct

Metanephric blastema: from the nephrogenic cord

Question 10

when does the mesonephric duct arise and what does it induce

Answer 10

arises during the 5th week: the caudal end of each mesonephric duct near the cloaca will induce the uteric bud

Question 11

when does the kidney functionally and definitively form and what is its main function

Answer 11

9-10th week, will have an excretory and collecting portion

main function is to make amniotic fluid

In the fetus the placenta gets rid of all the waste, not the fetal kidney

Question 12

what happens to the ureteric bud and how is the collecting system formed

Answer 12

the Ureteric bud will elongate and penetrate the blastema to form the renal pelvis

the stalk of the ureteric bud will become the ureter

The cranial part of the bud will branch and create the collecting tubules

• 1st generations (4) of tubules will enlarge to be the major calices
• 2nd generation (4) of tubules will become the minor calices

Question 13

5 steps of the nephron development

Answer 13

1) arched collecting tubule induces cells of metanephrogenic blastema to form metanephric vesicles
2) Vesicels will elongate to form metanephric tubules
3) Proximal end will form glomerular capsule, this will be invaded by glomeruli (blood vessels)
4) other end of the tubule lengthens and differentiates to PCT, DCT, and nephron loop as it lengthens
5) each DCT contacts an arched collecting tubule = now connected once fused at site of contact

repeat millions of times

Question 14

Does the kidney develop anymore nephrons after birth

Answer 14

no, whatever you have after birth is what you have for life

will have to go on dialysis

Question 15

how does the kidneys ascend

Answer 15

Permanent kidneys lie within the pelvis and will gradually ascend into the abdomen due to the caudal elongation

• mesonephros will degenerate as well
• Hilum rotates medially by 90 degrees
• 9th week will be in suprarenal glands

Question 16

what is the vasculature of the kidneys

Answer 16

Recieve blood supply from the vessels that are the closest

The first branch is from the common iliacs but as thwe kidneys ascend, the definitive renal arteries from the aorta will form and give the blood supply

the former branches will undergo involution and disappear

Question 17

Ureteric bud Embryonic structure gives rise to what adult structures?

Answer 17

Collecting portion

Ureter
Renal pelvis
Major and minor calyces
collecting ducts

Question 18

Them metanephric blastema will give rise to what adult structures

Answer 18

Excretory Portion

Bowmans capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule

Question 19

Unilateral renal agenesis

Answer 19

1:1000 more frequent in males

typically asymptomatic

lose a kidney

suspected in infants with 1 umbilical artery

Question 20

Bilateral renal agenesis

Answer 20

1: 3000

Oligohydraminos

Nonviable-pulmonary hypoplasia

Potter syndrome

Question 21

Duplications and the two types

Answer 21

Abnormal division of ureteric bud

Incomplete divison= divided kidney and bifed ureter

Complete division: double kidney and bifed ureter or separate ureters

Question 22

Horseshoe kidney

Answer 22

fusion of the inferior poles
asymptomatic
ascent can be prevented by Inferior mesenteric Artery

Question 23

Accessory Renal vessels

Answer 23

multiple renal arteries
-25 percent of adult kidneys

2x common as accessory veins

can obstruct the ureter and cause hydronephrosis

if ligated can cause ischemia

Question 24

Polycystic kidney disease

Answer 24

Autosomal recessive mutation of PKHD1

cysts present in both kidnes
renal insufficiency
25% associated with pulmonary hypoplasia

Question 25

Multicystic kidney disease

Answer 25

abnormal development of renal system

cysts are likely dilations of loop of Henle

normally only one kidney affected

Question 26

What is the Urogenital sinus and what is its three parts

Answer 26

Ventral cloaca (distal hindgut) contains the urogenital sinus and the anorectal canal
-these regions are seperated by the urorectal septum

the urogenital sinus is critical for bladder and urethral development

• vesical part - forms most of the urinary bladder
• pelvic part - forms neck of bladder and prostatic urethra (m) and urethra (f)
• Phallic part - forms the spongy urethra (m) and lining of the vaginal vestibule (f)

Question 27

sequence of the development of the connections to the bladder, and the trigone

Answer 27

between 4-6 weeks the mesonephric duct is incorporated into the posterior wall of the bladder
-uretric bud is also attached which will connect the openings of the ureteric buds into the bladder wall

openings of the mesonephric duct are carried inferiorly to the pelvic urethra

Forms the trigone, triangular region of the mesonephric and ureteric ducts that blend into the posterior bladder

Question 28

Bladder development and what tissues comes from what embryologically

Answer 28

Develops mainly from the vesical part of the urogenital sinus

Epithelium = endoderm (urogenital sinus)

Submucosa and muscularis = splanchnic mesoderm

Trigone = intermediate mesoderm (mesonephric ducts)

Question 29

since the bladder is continuous with the allantois, what happens to it during the development of the bladder

Answer 29

the allantois will constrict and form the urachus

• which extends from the apex of the bladder to the umbilicus
• happens as the superior portion of the bladder is established

then will form the median umbilical ligament still in our bodies today

Question 30

Exstophy of the bladder

Answer 30

ectopic vesicae

arises during the body folding during the 4th week

defective closure of the ventral abdominal wall

exposure of mucosa of the posterior wall of bladder

Question 31

Epispadis

Answer 31

urethral opening is on the dorsum of the genital tubercle rather than on its ventral side

can occur with the exstrophy of the bladder

Question 32

what are the three different Urachal Anomalies

Answer 32

Urachal cysts: reminants of the epithelial lining of the urachus that can become infected and enlarged

Urachal sinus: end of the urachus remains open into the bladder (inferior region) or umbilicus (superior region)

Urachal fistula: entire urachus remains patent and allows urine to escape from umbilical orifice
-leaking urine or discharge

Question 33

what are the three layers of the cortex and what do they secrete
medulla?

Answer 33

Zona glomerulosa: produces mineralocorticoids (regulate electrolytes)
Zona fasciculata: produces gluccocorticoids (regulate blood glucose, lipid metabolism)
ZOna reticularis: produces sex hormones, estrogen, and testosterone related hormones

Medulla: chromaffin cells which secrete NE and epi

Question 34

Development of the suprarenal gland

Answer 34

1) 5th week, coelomic epithelium delaminates and enters surrounding mesoderm to the fetal cortical cells
2) Neural crest cells will migrate into the medulla and differentiate to make the chromaffin cells

3) fetal cortex regresses (2nd month PN) and definitice cortical cells reorganize to make the zona glomerulosa, fasciculata, and reticularis (adult)
- come from the urogenital ridge

Question 35

What does the fetal cortex secrete from the suprarenal gland that is important for the mother

Answer 35

secretes dehydroepiandrosterone (DHEA) which is converted by the placenta to estradiol

helps in maintaing pregnancy and also secretes ACTH and gluccorticoids

Question 36

what is the embryological cell type that the capsule, cortex, and medulla come from in the suprarenal gland

Answer 36

capsule: mesonephric mesoderm
cortex: coelomic epithelium (somatic mesoderm)
medulla: NCC