Renal Embryo

Question 1

What do both the urinary and genital systems develop from?

Answer 1

Intermediate mesoderm

Question 2

What do both the urinary and genital systems initially drain into?

Answer 2

A common cavity, the cloaca

Question 3

What organs does the urinary system have?

Answer 3

Kidney, ureter, bladder, urethra

Question 4

What do the kidneys ultimately end up as?

Answer 4

bilateral paired organs located in the lumbar retroperitoneum

Question 5

What are the three overlapping kidney systems?

Answer 5

pronephros, mesonephros, metanephros (sequentially)

Question 6

Where does the pronephros develop? Is it functional?

Answer 6

Cervical region; nonfunctional and rudimentary, comes and goes away in 4th week

Question 7

As the pronephros involutes, what is formed? Where?

Answer 7

Mesonephros and mesonephric duct (Wolffian Duct). Upper thoracic to upper lumbar region

Question 8

What is each tubule of the mesonephric duct supplied by, and what does it end in?

Answer 8

Each tubule supplied by fetal aortae which ends in a “glomerulus” (primitive). Minimal
filtration, and there is drainage through the Wolffian duct into developing cloaca

Question 9

The mesonephric duct and a few tubules persist in ________, but disappear in ______

Answer 9

the male as part of the genital system; the female

Question 10

When does the metanephros and definitive kidney appear?

Answer 10

5th week

Question 11

What does the excretory system develop from? What’s it induced by?

Answer 11

Metanephric mesoderm; induced by developing tubules; urine production is at 10 weeks

Question 12

What does the duct/collecting system (ureter, pelvis, calyces) develop from?

Answer 12

Uteric bud (@ distal mesonephric duct)

Question 13

What is kidney development regulated by?

Answer 13

Epithelial-mesenchymal interaction! Mesenchyme initially expresses WT1, which goes on to
regulate other molecular players

Question 14

What are the minor calyces formed from? How is the renal pyramid formed?

Answer 14

2nd order tubules enlarge to absorb the 3rd and 4th generations and form minor calyces; 5th+
generations elongate and drain into the minor calyces forming the renal period

Question 15

What is congential polycystic kidney disease?

Answer 15

Cysts form from collecting ducts, resulting in renal failure in infancy (autosomal recessive). If it’s autosomal dominant, all segments of the nephron involved and delayed onset renal failure

Question 16

What’s multicystic dysplastic kidney?

Answer 16

Numerous ducts surrounded by undifferentiated mesenchyme. No nephrons. May lead to
involution and renal agenesis

Question 17

What’s Potter sequence?

Answer 17

Renal agenesis or severe malformation à anuria, oligohydramnios, pulmonary hypoplasia,
GU anomalies

Question 18

Briefly discuss Wilm’s Tumor (Nephroblastoma)

Answer 18

Pediatric tumor of the kidney that results from mutations in WT1 or WT2. Can be associated
with other anomalies. Survival ~ 90% after surgery, chemo, radiation

Question 19

Regarding the renal arteries, _____ branches usually disappear as more _____ branches are
created

Answer 19

inferior; superior

Question 20

The kidney will ascend and rotate to assume its position with the calyces and the arteries
medial. True or false

Answer 20

True; there are actually a wide range of anomalies of fusion, ascent, or rotation i.e.
‘horseshoe’ kidney, crossed ectopia of kidney, pelvic kidney

Question 21

What is the bladder and urethra derived from?

Answer 21

Cloaca

Question 22

What divides the cloaca into the anal canal and the UG sinus in the 4th-7th week?

Answer 22

urorectal septum

Question 23

What origin is the seminal vesicle?

Answer 23

Wolffian Duct (mesonephric duct)

Question 24

How is the trigone of the bladder formed?

Answer 24

Mesonephric duct gets absorbed into posterior bladder to form the trigone. Ureter rises
cranially as kidneys ascend. Trigone lining initially mesodermal in origin and then become replaced by endodermal lining à in cancers, not surprising that different things can happen in
the trigone of the bladder compared to the rest of the bladder

Question 25

What is the bladder formed by?

Answer 25

Upper part of UG sinus

Question 26

Bladder is in continuity with the _____. This structure obliterates to become a thick cord
urachus (________)

Answer 26

allantois; median umbilical ligament

Question 27

Where would you feel a urachal cyst in a baby?

Answer 27

Midline below the umbilicus

Question 28

What is the lower, narrow part of the UG sinus?

Answer 28

Urethra