Renal Development - Severson

Question 1

What are the contributions of the pronephric kidney (AKA = forekidney) to the mature adult kidney?

Answer 1

Pronephros (mesoderm) arises in the cervical region and gives rise to the pronephric duct that grows caudally and opens into the cloaca.

Question 2

What are the contributions of the mesonephric kidney (AKA = mid-kidney) to the mature adult kidney?

Answer 2

Mesonephros (mesoderm) gives rise to the mesonephric tubules that become the efferent ductules of the male testis.

Mesonephric duct (extension of the pronephric duct) gives rise to the ductus deferens in males

Also gives rise to the ureteric bud in males and females (metanephric diverticulum)

Question 3

What are the contributions of the metanephric kidney (AKA hindkidney/definitive kidney) to the mature adult kidney?

Answer 3

Becomes the Ureteric bud => initiates the formation of the definitive kidney (stimulating differentiation of the metanephric mesoderm into the tubules of the permanent or definitive kidney)

Includes: ureter, renal pelvis, the major and minor calyces, the collecting ducts

Question 4

What are the various positional changes in the developing kidney?

Answer 4

Metanephric kidneys are initially located deep in the pelvic region, but undergo a shift or migration that moves them into the abdominal region.

This “migration” results from a rapid growth of the caudal embryo giving the appearance of kidney ‘ascent’.

Question 5

What are the changes in blood supply for the developing kidney?

Answer 5

Initially, the permanent kidney receives its blood supply from the common iliac arteries.

As the caudal regions of the body grow, the kidneys appear to ascend and receive their blood supply from progressively more superior parts of the abdominal aorta.

Question 6

How could the blood supply to the kidneys potentially cause hydronephrosis?

Answer 6

If multiple renal arteries form:

Failure of segmental blood supply to regress during development.

Blood vessels passing in front of ureter may block the flow of urine to the urinary bladder => hydronephrosis

Question 7

Is renal agenesis usually bilateral or unilateral (if so, which side)? More common in males or females?

Answer 7

Usually unilateral and on the left, and more common in males

Question 8

What should be suspected in infants with a single umbilical artery?

Answer 8

Renal agenesis

Question 9

What happens in bilateral renal agenesis?

Answer 9

Death shortly after birth

Question 10

What causes a duplicated or branched ureter?

Answer 10

Due to bifurcation of ureteric bud

Question 11

What causes a supernumerary kidney?

Answer 11

Due to division of the ureteric bud prior to interaction with the metanephric mesoderm.

Question 12

What is the result of a ureter entering a urogenital sinus derivative at some site other than the dorsolateral wall of the urinary bladder?

Answer 12

Ectopic ureter

Question 13

What blood vessel blocks the migration/ascent of a horseshoe kidney?

Answer 13

Inferior mesenteric artery

Question 14

What divides the cloaca into the rectum and the urogenital sinus during development?

Answer 14

Urorectal septum (mesoderm)

Question 15

The Urogenital sinus is continuous with what structure that extends into the body stalk and later forms the urachus that eventually becomes the median umbilical ligament?

Answer 15

Allantois

Question 16

The epithelium of the entire bladder is derived from what embryological tissue?

Answer 16

Endoderm (of the urogenital sinus)

Question 17

How is the Trigone of the Bladder formed?

Answer 17

Mesonephric ducts and uteric bud are incorporated into the posterior wall of the developing urinary bladder

Question 18

The urorectal septum fuses with the cloacal membrane to complete the division of the cloaca. This site of fusion becomes what major adult structure?

Answer 18

Perineal body

Question 19

What are the three derivatives of the Urogenital sinus?

Answer 19

(1) Vesicle part of the urogenital sinus forms the urinary bladder and is continuous with the allantois
(2) Pelvic (middle) part becomes the bladder neck and the prostatic urethra in the male and the entire urethra in the female
(3) Phallic part grows toward the genital tubercle and forms the penile urethra

Question 20

What embryological tissue(s) give rise to the male urethra?

Answer 20

Proximal male urethra is part of original urogenital sinus (endoderm)

Distal male urethra derived from ectodermal cord (ectoderm)

Question 21

What embryological tissue(s) give rise to the female urethra?

Answer 21

All of female urethra derived from urogenital sinus (endoderm)

Question 22

What happens when secretions are produced by the epithelial cells in the urachus that do not degenerate?

Answer 22

Epithelial cells that may remain could form urachal cysts, or a portion of the urachus could drain via the umbilicus as in the case of a urachal sinus, or the urachus could remain patent so the urine would dribble from the umbilicus.

Question 23

What happens when there is a lack of anterior wall mesoderm due to failure of the mesenchymal cells to migrate between the ectoderm of the abdomen and cloaca during the fourth week of development?

Answer 23

Exstrophy of the bladder

-the anterior wall of the bladder (urogenital sinus) degenerates, exposing the interior of the bladder

Question 24

What causes Megacystis or Megalocystis? Complications?

Answer 24

presence of posterior urethral valves that block the outflow of urine from the urinary bladder (only in the male)

Blockage of urinary outflow could lead to renal failure, and pulmonary hypoplasia due to bladder wall pressure on the developing thorax

Question 25

How does the Adrenal Gland develop?

Answer 25

Adrenal medulla develops from neuroectoderm that gives rise to neural crest cells that migrate to the area of the developing adrenal gland.

Adrenal cortex develops from mesoderm.

Both a fetal and permanent cortex develop, with the fetal cortex degenerating during the first year after birth.

Question 26

What are the contributions of the metanephric blastema to the mature adult kidney?

Answer 26

Nephrons: Bowman’s capsule, PCT, loop of Henle, and DCT