L15 – Development of the Urinary System Flashcards Preview

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Flashcards in L15 – Development of the Urinary System Deck (107):
1

Which phase of development has most susceptibility to teratogens?

Highest in embryonic period (1st trimester = development
of important structures)

2

What are teratogens?

genes that cause specific malformations

3

What 4 organs are in the urinary system?

Kidneys, ureter, urinary bladder, urethra

4

What are the three germ layers?

Endoderm, mesoderm, ectoderm

5

What are the three divisions of mesoderm?

Paraxial, intermediate, Lateral

6

What is the central axis of mesoderm?

notochord

7

Name two things that arise from paraxial mesoderm

musculoskeletal structures
Somites

8

Where does the urogenital system arise from?

Intermediate mesoderm

9

Where along the embryo does the intermediate mesoderm extend along?

Dorsal body wall of embryo

10

In what direction does the embryo fold?

in horizontal plane

11

What happens to intermediate mesoderm as the embryo folds?

Intermediate mesoderm is carried ventrally

loses connection with paraxial mesoderm (somite)

12

How is urogenital ridge formed?

Mesoderm elevates longitudinally on each side of dorsal aorta

forms urogenital ridge / fold

13

What does urogential ridge give rise to?

Nephrogenic cord / ridge (parts of urinary system)

14

What happens to nephrogenic cord after its formation?

form 3 sets of tubular nephric structures/ 'nephros'

15

What are the three sets of nephros?

Pronephros, Mesonephros, Metanephros

16

Describe direction of nephros formation

Temporally and Spatially- head to tail

17

When do the three sets of nephros start to appear?

Pronephros = 4th week
Mesonephros= Late 4th - 5th wk
Metanephros = Early 5th wk

18

Describe the cell group of pronephros and location relative to somites.

7-10 solid cell group (cell clusters, tubular structures)

5th -7th cervical somite region

19

Describe the cell group of mesonephros and location relative to somites.

Large, elongated, excretory organs

14th-26th somites (cervical-lumbar)

20

When does mesonephros appear during?

regression of pronephros

21

In the 5th week which two nephros overlap?

meso and metanephros

22

What happens to rudimentary pronephros? What structure persists?

Rudimentary pronephros soon degenerate (cervical)

Most of Pronephric ducts persist

23

How does pronephric duct develop?

Run caudally (to tail) and
open into cloaca

Utilized by the next set of the kidneys (mesonephros, metanephros)

24

What is the primary function of mesonephros?

Function as interim kidneys for about 4 weeks

25

Location of mesonephros?

extends from upper thoracic to upper lumbar region

26

What structures make up mesonephros?

Glomeruli
Mesonephric tubules within Nephrogenic cord

27

What structure extends from Cloaca?

Allantois

28

What structures branch from the mesonephric duct?

Mesonephric tubules

29

What structure is between the nephrogenic cord and Cloaca?

Ureteric bud

30

Which parts of mesonephric tubules and cords regress?

more cranial mesonephric tubules and cords regress
(atrophy)

31

Which parts of the mesonephric tubules and cords remain?

The distal tubules and
cords differentiate into
final ductal system

32

How does the aorta connect with the mesonephric duct?

(central) Dorsal aorta > Glomerulus > mesonephric tubule> mesonephric duct (lateral)

33

In females, when do the mesonephric ducts disappear? How about in males?

Female: ducts disappear by 16th week

Mesonephric ducts (cuboidal epithelium) persist as ductus deferens in adults

34

What is another name for mesonephric duct in male?

Wolffian duct

35

What degenrates along with mesonephric kidney?

Paramesonephric duct

36

What forms part of the permenant kidneys?

metanephros

37

Which parts of the mesonephric tubules regress and which parts develop?

Cranial mesonephric tubules and cords regress/ atrophy

Distal tubules and cords differentiate

38

What gives rise to the drainage system of permanent kidneys? Origin?

Ureteric bud/ metanephric diverticulum


outgrowth/protrusion of distal mesonephric duct near its entrance into cloaca

39

What are the two functional components/ Primordia in forming permanent kidneys?

ureteric bud (collecting portion)

metanephric blastema (excretory portion)

40

Compared to ureteric bud, where is metanephric blastema derived from?

Ureteric bud is dervied from distal mesonephric duct

Metanephric blastema is derived from caudal part of nephrogenic cord

41

How are uterteric bud and metanephrogenic blastema arranged?

Metanephrogenic blastema surrounds ureteric bud

42

How does the ureteric bud develop whilst surrounded by metanephrogenic blastema?

Distal mesonephric duct/ ureteric bud branches, forming ureteric trunks and ureteric branches

43

Why does ureteric bud branch?

larger surface
area

44

How long does it take for metanephros to start functioning?

4 weeks of development

45

What 4 structures of the permanent kidney does ureteric bud give rise to?

Major and minor calyces
Papillary duct
Collecting tubule
Ureter

46

What 4 structures of the permanent kidney does metanephric blastema give rise to?

 Bowman’s capsule
 Proximal convoluted tubule
 Loop of Henle’s
 Distal convoluted tubule

47

How does ureteric bud and metaphric blastema join?

Canalization with collecting duct to establish link between excretory and collecting system

48

What are the orders of ureteric bud divisions?

 1st-4th order:
major, then minor calyces
 5th order: papillary duct
 6th-14th order: collecting
tubules

49

What specific nutrient influence renal organogenesis?

Vitamin A (retinoids)

50

How does absence of ureteric bud manifest?

renal agenesis (no kidney): unilateral (1 side) / bilateral (2 sides: almost fatal)

51

How does Incomplete
division of ureteric bud manifest?

divided kidney + bifid ureter
(= 2 ureters)
Ectopic kidney

52

How does complete division of ureteric bud manifest?

supernumerary kidney + bifid ureter

53

How does a second ureteric bud manifest?

2 ureteric buds =
supernumerary kidney (3rd kidney)

54

How does left kidney migration to right side manifest?

Unilateral double kidney

55

How does fusion abnormalities manifest?

Horseshoe/ Discoid kidney
Interfere inferior mesenteric artery

Rosette kidney (rounded and joined)

Duplex kidney: partially duplicated collecting system (2 ureters)

56

What is Sequential & Reciprocal Induction in permanent kidney formation?

Ureteric bud and
metanephric blastema
interact and induce each
other to differentiate

57

How does sequential and reciprocal induction change the metanephric tissue caps?

transform metanephric
mesenchyme to epithelia

58

Which gene is most essential in sequential and reciprocal induction?

WT1: essential in normal kidney development

59

Explain how WT1 can malfunction.

Homozygous recessive (rare)
Wilms tumor 1 mutation: incomplete mesenchymal-to-epithelial transformation, but transform into cancerous cells

60

What is polycystic kidney disease?

Holes between ureteric bud and metanephric blastema

Cysts larger than nephron

61

There are two kinds of polycystic kidney disease. Name and incidence rate?

COMMON:
Autosomal dominant
polycystic kidney disease
(ADPKD): 1-2 per 1000 births


RARE:
Autosomal recessive polycystic
kidney disease (ARPKD): ~1 in 20,000-40,000

62

How does PKD come about?

Mutation of PKD1 & 2 gene

Ureteric bud and metanephric blastema anomaly

63

How does the kidney transition in the body?

Kidney ascends and rotates from pelvic to lumbar region (L2)

64

How does the hilum of the kidneys change as it ascends and rotates?

Original hilum is ventral, rotate to medial

65

What brings about the ascend of the kidneys?

The kidneys do not actually move across body compartments.

Depends on differing growth of Sacral and Lumbar regions

66

What other structure grows as kidneys ascend and rotate?

Growth of ureter

67

Explain the change in kidney blood supply as the kidney ascends. *blood vessels do not follow the kidney*

Metanephros at pelvis = middle sacral arteries/common iliac arteries

Transitional vessels that disappear/ degenerate later

Finally upper lumbar arteries

68

What congenital anomalies can occur with transitionary vessels?

 Aberrant renal arteries
 Accessory (supernumerary) renal arteries
 Polar renal artery may obstruct ureter

69

What prevents the right kidney from ascending higher?

Right lobe of liver prevents right kidney to ascend as far as that on the left

70

What is a congenital condition in kidney ascending?

Ectopic kidney or unilateral double kidney

71

What supplies the suprarenal/ adrenal glands?

Suprarenal arteries (from
aorta)

72

What is persistent lobulation?

 Fetal kidneys are subdivided into lobes
 Lobulation usually
disappears during infancy

73

Which 2 types of dysgenesis of kidney is possible?

Renal hypoplasia (undergrowth): unilateral /
bilateral

Renal dysplasia: renal cysts

74

What structure is continuous with Cloaca and the lumen is later obliterated?

Allantois

75

What divides the cloaca into two portions? When does this occur?

urorectal septum
4th-7th week

76

What are the two divded portions of the cloaca?

1. Posterior portion = anorectal canal (hindgut for fecal matter)

2. Anterior portion = primitive urogenital sinus (for urine)

77

What does urogenital sinus later contribute to ?

Bladder, urethra

78

How does the urogenital sinus later divide and what if formed from each part?

1. Vesical (proximal) part (upper,largest) = forms part of bladder
2. Pelvic (middle) part forms prostatic, membranous urethra
3. Phallic (distal / lower) part forms penile urethra

79

What 2 things is allantois subdivided into?

Vesico-urethral canal
Urachus

80

What is the fate of the two subdivisions of the allantois?

vesico-urethra canal forms urinary bladder

Urachus becomes obliterated and becomes thick fibrous cord- median umbilical ligament

81

Where is urachus attached to on the bladder?

connected to apex of bladder

Extends along posterior
surface of anterior abdominal wall

82

What structure outgrows to form ureter? What part of it dilate to form a part of bladder wall?

Outgrowth / extension of mesonephric duct

Terminal ends of mesonephric ducts dilate > become trigone (triangular, smooth part of bladder wall)

83

What is trigone later covered by?

covered by ENDODERMAL***
epithelium (transitional)
from surrounding cloaca and
allantois > sensitive to
expansion and signal urination

84

What three congenital anomalies of the urachus are there?

(most common to least)
Urachal cyst
Urachal sinus (hollow cavity)
Urachal fistula (abnormal connection)

85

How do the three urachus anomalies come about?

Urachal cyst:
Arise from remnants of epithelial lining of urachus

Urachal sinus (hollow cavity):
Superior part of urachus lumen may remain patent
Inferior part maybe patent


Urachal fistula (abnormal connection):
Entire urachus remains patent > allows urine to escape from its umbilical orifice

86

When does urorectal septum completely seperate cloaca?

Complete separation of liquid and solid into 2 cloaca compartments at 8 weeks

87

What is female perineal body?

central tendon of perineum

mass of interlocking muscular, fascial, and fibrous components lying between vagina and anorectum

88

What three components are there that form bladder?

Primitive urogential canal from divided cloaca

Extending mesophrenic duct forming trigone

Vesico-urethral canal from divided Allantois

89

Why is female perineal body important?

Essential for integrity of pelvic floor

Provides attachment to muscles

90

There are 6 congenital anomalies to ureter development. Try and name a few?

 Double pelvis of ureter
 Bifid ureter
 Ectopic ureteric orifice
 Postcaval ureter (behind vena cava)
 Atresia of ureter(absence)
 Ureterocele: distal ureter balloons at its opening into bladder > sac-like pouch

91

The connective tissue and smooth muscle of both sexes' urethra are derived from where?

splanchnic mesenchyme (endoderm, mesoderm)

92

What are the three parts to male urethra? Where are these parts developed from?

Vesical part - bladder
Pelvic part- prostatic and membranous
Phallic part- penile, enclosed by urethral fold

from urogenital sinus

+ glans urethra from ectoderm

93

What part of the adult spongy/ penile urethra is not derived from urogenital sinus?

Glans urethra

94

How does the phallic urethra become continous with external environment?

Glans urethra, solid cord of ectodermal cells, ingrowth and canalize with terminal phallic urethra

95

How does the female urethra and male urethra differ in germ layer origin?

Male= endoderm and ectoderm
Female= only endoderm

96

Female urethra is formed how?

neck of primitive bladder elongates to form entire urethra

97

oligohydramnios (low amniotic fluid volume) causing Potter sequence anomalies is a result of what dysfunction?

renal agenesis, hypoplasia, or dysfunction in utero

98

Unlike other parts of the urinary system, the urethra is not...? (in origin)

Not originate from the mesoderm

99

What are 2 features at the terminal end of the spongy penile urethra in male?

Navicular fossa = pouch like end of urethra

Prepuce= foreskin

100

What does the MEDIAN umblilcal ligament lie between?

MEDIAL umbilical ligaments which are fibrous remnants of umbilical arteries

101

What causes exstrophy of bladder?

Ventral body wall defect, exposing urinary bladder mucosa on abdominal wall

102

What are the three congenital anomalies to urethra development in male?

Meatus Stenosis
Narrow opening of external meatus, urethral stenosis

Hypospadias
Urethral Openings on the underside of penis instead of at tip

Episadias
Urethral opening on top of penis. Wide seperation of pubic bone and complete exstrophy of bladder

103

Summarize the origin of kidneys.

Ureteric bud and metanephric blastema

104

Ureter origin?

Outgrowth of mesnephric duct

105

Urinary bladder origin?

Urogenital sinus
Vesico-urethral canal
Extending mesophrenic duct

106

Urethra: female and male origin?

Female = endoderm, elongation of primitive bladder

Male: urogenital sinus, surface ectoderm

107

Anus origin?

urorectal canal from cloaca

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