3.7.4. Urinary Tract Development

Question 1

urachus

Answer 1

distal portion of the allantois; it becomes a fibrous cord and forms the medial umbilical ligament

Question 2

urachal cysts

Answer 2

result of a patent urachus (accumulation of fluid within the medial umbilical ligament)

Question 3

urogenital ridge

Answer 3

covered elevation of intermediate mesoderm that lies in the lower thoracic and lumbar regions and forms the mesonephric kidneys

Question 4

apoptosis

Answer 4

programmed cell death

Question 5

intermediate mesoderm

Answer 5

mesoderm-derived layer lying between the paraxial and lateral plate layers and responsible for forming much of the urogenital system

Question 6

WTI gene product

Answer 6

Wilms’ tumor gene: stimulates the induction of growth via the ureteric bud

Question 7

pronephros

Answer 7

rudimentary, nonfunctional kidney precursor; forms vestigial excretory units called nephrotomes

Question 8

Wilms’ tumor

Answer 8

kidney cancer that typically occurs in children

Question 9

pronephric duct

Answer 9

predecessor of the Wolffian duct

Question 10

Renal agenesis

Answer 10

condition in which one or both kidneys fail to develop

Question 11

mesonephros

Answer 11

intermediate kidney with short span of function (5-10 weeks of embryological life); formation of the glomerulus and bowman’s capsule. Site of the urogenital ridge

Question 12

dysplastic kidney

Answer 12

condition that results from malformation of the kidney during fetal development. consists of irregular cysts of varying sizes and has no function

Question 13

mesonephric duct

Answer 13

the longitudinal collecting duct

Question 14

potter sequence

Answer 14

atypical physical appearance of a fetus or neonate due to oligohydramnios

Question 15

mesonephric tubules

Answer 15

genital ridges that are next to the mesonephros

Question 16

trigone

Answer 16

smooth triangular region of the internal urinary bladder formed by the two urethral orifices and the internal urethral orifice

Question 17

metanephros

Answer 17

definitive kidney developed from the mesonephros; formation of the collecting ducts

Question 18

cloacal membrane

Answer 18

portion of the cloaca that septates to give rise to the urogenital sinus and the anorectal canal

Question 19

nephron

Answer 19

functional unit of kidney consisting of the proximal and distal convoluted tubes, loop of henle, bowman’s capsule, and a glomerulus

Question 20

allantois

Answer 20

vestigial structure that serves as a respiratory and waste storage organ for embryos

Question 21

ureteric bud

Answer 21

gives rise to the ureter, the renal pelvis, the major and minor calyces, and 1-3 million nephrons; an outgrowth of the mesonephric duct close to the cloaca that induces differentiation of the metanephric system

Question 22

urogenital sinus

Answer 22

anterior portion of the cloacal division; gives rise to the urinary tract

Question 23

metanephric tissue cap (blastema)

Answer 23

mass of intermediate mesodermal cells around the distal end of the metanephric diverticulum that give rise to nephrons in the permanent kidneys.

Question 24

perineal body

Answer 24

pyramidal fibromuscular mass in the middle of the perineum.

Question 25

exstrophy of the bladder

Answer 25

a ventral body defect in which the bladder mucosa is exposed; results in an open urinary tract that extends along the dorsal aspect of the penis through the bladder to the umbilicus

Question 26

median umbilical ligament

Answer 26

adult remnant of the urachus

Question 27

epithelial/mesenchymal interactin

Answer 27

when signals pass back and forth between these two cell types to regulate organ differentiation

Question 28

characteristics of pronephros

Answer 28

1. first kidney to form 2. intermediate mesoderm condenses to form epithelial buds 3. pronephri in humans do not differentiate into functional excretory units 4. disappear by 24 days 5. functional excretory units within 6-10 weeks 6. Remnants of tubules differentiate into structures of male and female reproductive systems

Question 29

mesonephros characteristics

Answer 29

1. Middle kidney which contains simple nephrons and is functional 2. early in the 4th week, mesonephric ducts develop, extend caudally and fuse with the walls of the cloaca on day 26 3. early in the 4th week, mesonephric ducts induce the intermediate mesoderm to form about 40 mesonephric tubules. Induced by pronephros 4. remnants of tubules differentiate into reproductive system structures

Question 30

metanephros characteristics

Answer 30

1. definitive kidney derived from the metanephric diverticulum which induces formation of metanephric blastema 2. Composed of excretory and collecting system

Question 31

where is excretory system formed?

Answer 31

metanephric mesoderm

Question 32

where is collecting system formed?

Answer 32

mesonephric duct (ureteric buds). The ureteric buds sprout from the mesonephric duct and penetrate the metanephric blastema

Question 33

synthesis of BMP7 and FGF2 allow for what?

Answer 33

maintenance of WTI which allows for differentiation of nephrons

Question 34

What forms the minor calyces?

Answer 34

tubules of the 2nd, 3rd, and 4th subdivisions fuse to form the minor calyces of the renal pelvis

Question 35

What forms the renal pyramid?

Answer 35

tubules of the 5th and later divisions that have elongated.

Question 36

portions of the cloaca?

Answer 36

urogenital and rectal portions. Furthermore, the urorectal septum divides the cloaca and yields the formation of the urinary bladder and the urogenital sinus

Question 37

What is a horseshoe kidney?

Answer 37

abnormal ascent of a single kidney that gets caught under the inferior mesenteric artery. More common in males.

Question 38

What are bifid ureters?

Answer 38

Two ureters that share a common opening into the bladder.

Question 39

What is an ectopic ureter?

Answer 39

It is an extra ureter that does not open into the urinary bladder. The original upper ureter opens into the abdomen and causes incontinence.

Question 40

Describe potter syndrome

Answer 40

Presented by a baby with bilateral renal agenesis. Associated with: Pulmonary hypoplasia, Oligohydramnios (the trigger event), Twisted face, Twisted skin, Extremity defects, Renal failure.

Question 41

Describe the multicystic dysplastic kidney

Answer 41

Caused by an abnormal interaction between a ureteric bud and metanephric mesenchyme. This leads to a nonfunctional kidney consisting of cysts and connective tissue. If unilateral, is generally asymptomatic. Diagnosed prenatally via ultrasound

Question 42

vas deferens arises from where?

Answer 42

mesonephric (wolffian) duct

Question 43

What are the embryological sources for the suprarenal glands?

Answer 43

intermediate mesoderm for the cortex and neural crest for the medulla. Differentiation occurs during the 5th week of development.