Urinary System Development

Question 1

Urinary and reproductive duct systems develop from ____

Answer 1

Intermediate mesoderm

. Urinary system first,t hen reproductive track later

Question 2

Urogenital ridges

Answer 2

. Week 3
. Intermediate mesoderm condenses into 2 columns
. Located along dorsal wall do developing thoracoabdominal cavity in surface coelomic epithelium
. Each ridge has nephrogenic ridge and gonadal ridge

Question 3

Nephrogenic ridge

Answer 3

. Lateral portion of urogenital ridge

. Parts of urinary system and reproductive ducts develop

Question 4

Gonadal ridge

Answer 4

. Med. portion of urogenital ridges

. Gonads form from this

Question 5

Pronephros

Answer 5

. Well 3
. Form as few sets of tubules in cervical regions of nephrogenic ridge
. Multiple tubules unite to form pronephric duct that grows caudally and connects to cloaca
. Tubules degenerate in week 4, but duct persists

Question 6

Cloaca

Answer 6

. Primitive tail-end cavity into which developing intestinal, genital, and urinary tracts open

Question 7

Mesonephros

Answer 7

. Week 4
. In thoracic and lumbar regions of nephrogenic ridges as collection of tubules and clusters of capillaries (glomeruli)
. Larger than pronephroi
. Tubules connect to pronephric duct then matures to be mesonephric duct (Wolffian duct)
. Briefly functional
. Tubules degenerate by week 8, derivatives of duct persist as ureters, part of bladder, and parts of male reproductive tract

Question 8

Metanephros

Answer 8

. Week 5
. Final definitive kidneys
. Form from ureteric buds and metanephric mesoderm
. Paired ureteric buds branch from caudal mesonephric ducts near cloaca
. Layer of metanephric mesoderm at caudal end of nephrogenic ridge coalesce around ureteric buds and proliferates to become nephrons
. Distal portion of mesonephric ducts form ureter and bladder trigone

Question 9

Ureteric buds differentiate to form ___

Answer 9

. Renal pelves
. Major and minor calyces
. Collecting ducts of kidneys

Question 10

Nephron development

Answer 10

. Proximal end of nephron forms Bowman’s capsule
. Middle portion elongates to form proximal and distal convoluted tubules and loop of Henle
. Distal end of each nephron connects to collecting duct

Question 11

Ascent of kidneys

Answer 11

. Metanephric kidneys migrate from pelvis into upper abdomen as thorax elongates
. Kidneys rotate 90 degrees so hilus faces medially
. As kidney ascends, arterial supply occurs via progressively more cranial branches of aorta
. More caudal vessels involuted as higher vessels take over their duties

Question 12

Embryonic kidney function

Answer 12

. Metanephric kidneys are fully functional by week 12
. Fetal urine is excreted into amniotic sac which helps maintain amniotic fluid volume
. Fetus swallows amniotic fluid that then absorbs into loud stream and recycles through developing kidneys

Question 13

Ectopic pelvic kidney

Answer 13

. Occurs when metanephric kidney fails to ascend into upper abdomen
. Kidney is usually fully functioning but is located in pelvic or lower abdominal cavity

Question 14

Horseshoe kidney

Answer 14

. Occurs when 2 ureteric bud fuse causing single U-shaped kidney
. Lies at L3-5 level
. Normal kidney ascent during embryonic development is prevented as fused kidney is trapped inf. To root of inf. Mesenteric a.

Question 15

Accessory renal vessels

Answer 15

. Defect in normal development and degeneration of successive aortic branches as kidney ascends
. More inf. Located vessels usually degenerate as sup. Vessels appear, but errors in process result in accessory vessels

Question 16

Bilateral renal agenesis

Answer 16

. Oligohydraminos due to failure of kidneys to develop

. Results in pulmonary hypoplasia and is fatal w/in few days of birth

Question 17

In pelvic region, the cloaca is continuous w/ what superiorly and what posteriorly?

Answer 17

. Allantois superiorly

. Hindgut posteriorly

Question 18

What does cloaca derive from?

Answer 18

Endoderm of primitive gut tube

Question 19

Cloaca subdivides to provide separate passages for what structures?

Answer 19

Anus and urethra

Question 20

Urorectal septum

Answer 20

. Week 6
. Wedge of mesoderm tha subdivides cloaca into ant. And post. Portions
. Grows outward to reach body wall where it contributes to perineal body

Question 21

Anorectal canal

Answer 21

. Post. Portion of subdivided cloaca

. Becomes rectum and anal canal

Question 22

Urogenital sinus

Answer 22

. Ant. Portion of subdivided cloaca

. Further subdivides into vesicle portion, pelvic portion,and phallic portion

Question 23

Vesicle portion of urogenital sinus

Answer 23

. Primitive bladder and is continuous w/ allantois
. Epithelium lining bladder from endoderm
. Lamina propria, smooth muscles, and serosa/adventitia from splanchnic mesoderm
.

Question 24

Trigone formation of bladder

Answer 24

. Forms from mesonephric ducts

. Become incorporated into post. Wall of bladder lined by endodermal epithelium

Question 25

Urachus

Answer 25

. Fibrous cord that arises when allantois degenerates
. Attaches bladder apex to abdominal wall
. Becomes median umbilical ligament

Question 26

Pelvic portion of urogenital sinus

Answer 26

. Narrow canal

. Forms prostatic and membranous portions of male urethra

Question 27

Phallic portion of urogenital sinus

Answer 27

. Definitive urogenital sinus
. Develops into penile urethra in males
. Urethra, vaginal vestibule, and inf. 1/3 part of vaginal canal in females

Question 28

Urethral development by end of month 3

Answer 28

. Epithelium of prostatic urethra in males and urethra in females proliferates and forms outgrowths that penetrate into surrounding visceral mesoderm
. Males: bud to form prostate gland
. Female: buds give rise to paraurethral (SKene’s) glands

Question 29

Urachal fistula

Answer 29

. Failure of allantois to close
. Forms btw urachus and bladder
. Urine leaks from umbilicus

Question 30

Urachal cysts

Answer 30

. Isolated portions of allantois may also persist

. Along length of urachus/median umbilical ligament