Embryology

Question 1

mesonephros

Answer 1

second set of kidneys that form at end of week 4 from the intermediate mesoderm
- will become functional nephrons that work until month 3
- in lower thoracic, upper lumbar
drain into mesonephric duct—>cloaca

Question 2

Metanephros

Answer 2

functional at end of 3rd mo. from intermediate mesoderm
the definitive kidney
a) metanephric blastema: directly from intermediate mesoderm–>nephron
b) Ureteric bud: diverticula from the mesonephric duct

Question 3

metanephric blastema

Answer 3

forms all parts of the nephron

from intermediate mesoderm

Question 4

ureteric (metanephric) bud

Answer 4

forms everything from collecting tubules—>ureter

just a bud from the mesonephric bud

Question 5

Kidney ascent

Answer 5

move from pelvis up to abdomen by week 9
receive new vessels and innervation as they go up,
lower vessels regress
rotate 90deg so that hilum faces medially

Question 6

accessory renal artery/vein

Answer 6

when lower vessels do not regress during ascension
- generally asymptomatic
can cause compression of ureter —>hydronephrosis (backup of urine)

Question 7

renal hypoplasia

Answer 7

from inadequate branching of ureteric bud and lack of differentiation of nephrons

very small kidney with few (functional) nephrons

• asymptomatic if unilateral
• can be persistent fetal lobulation

Question 8

Cystic diseases

Answer 8

functional kidney replaced by large cysts
present at birth—>decreased renal function
multicystic dysplastic kidney and polycystic kidney
Autosomal recessive=cysts from collecting ducts (+renal insufficiency)

Autosomal dominant: cysts from collecting ducts and nephron

Question 9

real agenesis

Answer 9

complete lack of renal formation
ureteric bud fails to form, or it does not have signaling to induce formation of metanephric blastema
regression of bud etc
**adrenal gland is fine

Question 10

Potter’s sequence

Answer 10

bilateral renal agenesis
non-compatible with life due to fetus not producing urine
(can also be caused by amniotic membrane)
**due to oligohydramnios: hypoplastic lungs, Potter’s face, club foot

Question 11

ectopic kidney

Answer 11

that does not ascend

pelvic kidney most common

Question 12

horseshoe kidney

Answer 12

inferior parts of L and R fuse in the pelvis
ascent is blocked by inferior mesenteric a
usually asymptomatic .

Question 13

Wilm’s tumor

Answer 13

very malignant tumor that originates in the kidney and moves towards the lungs
presents in childhood
- from WT1 gene mutation
—>un-differentiated and rapidly dividing intermediate mesoderm

associated with Denys-Drash syndrome
gonadal dysgenesis

Question 14

WAGR syndrome

Answer 14

WT1 and PAX6 gene mutation

- wilms+ gonadal dysgeneis+ eye problems+mental retardation

Question 15

Duplication of ureter

Answer 15

splitting of the ureter
caused by splitting of ureteric bud
can sometimes lead to duplication of kidney as well

Question 16

ectopic ureter

Answer 16

from 2 ureteric buds
forms 2 separate ureters
the lower of the two is the normal one, the upper one is often abnormal (dilated, drains to abnormal site-i.e. urethra, vagina, vestibule)

Question 17

urachal fistula

Answer 17

allantosis/ urachus remain patent

bladder—>umbilicus (ssx: urine from umbilicus)

Question 18

exstrophy of bladder

Answer 18

ventral wall defect
when the ventral pelvic wall does not fuse completely
bladder forms externally
extrophy of cloaca is more severe (associated w/ exposure of inner bladder and rectum with imperforate anus and epispadias)

Question 19

Urorectal septum

Answer 19

layer of tissue that divides cloaca and anterior urgenital sinus and the rectum/anal canal

Question 20

Urogenital sinus: cranial (vesical) potion

Answer 20

forms bladder (not trigone-from mesonephric duct)

continuous with allantois (which becomes urachus, which will become the median umbilical ligament)

Question 21

Urogenital sinus middle (pelvic) portion

Answer 21

forms urethra in females

forms prostatic and membranous urethra in males

Question 22

caudal (phallic) portion of the urogenital sinus

Answer 22

forms penile urethra