B6-012 Early Development of the MSK System

Question 1

what germ layers do skeletal muscles arise from? [2]

Answer 1

paraxial mesoderm
somatic lateral plate mesoderm

Question 2

what germ layer does smooth muscle arise from? [3]

Answer 2

splanchnic lateral plate mesoderm
ectoderm
neural crest

Question 3

what germ layer do teeth arise from?

Answer 3

neural crest

Question 4

arises from somitomeres and somites

Answer 4

skeletal muscle

Question 5

determine migratory paths of neural crest cells and spinal nerves

‘building blocks” for body plan

Answer 5

somites

Question 6

the ventral region of the epithelialized somite forms the […] while the remainder forms the […]

Answer 6

sclerotome
dermamyotome

Question 7

sclerotome derivatives [3]

Answer 7

ribs
rib cartilage
vertebrae

Question 8

myotome derivatives [3]

Answer 8

back muscles
shoulder girdle
body wall

Question 9

dermatome derivatives

Answer 9

connective tissue of dermis and back

Question 10

partial or complete loss of abdominal musculature

organs visible through abdominal wall

Answer 10

prune belly syndrome

Question 11

causes of prune belly syndrome [2]

Answer 11

incomplete development of abdominal muscles lead to urinary abnormalities

abnormality in bladder and accumulation of urine leads to muscle wasting

Question 12

limb buds develop at the end of week

Answer 12

4

Question 13

the mesenchymal core of the limb buds form [2]

Answer 13

bone and connective tissue

Question 14

the cuboidal ectoderm of the limb buds forms

Answer 14

apical ectodermal ridge

Question 15

the apical epidermal ridge forms the […] axis

Answer 15

proximal-distal

Question 16

what factors proliferate near the AER to allow limb lengthening?

Answer 16

FGF4 and 8

Question 17

as the limb grows, the cells closest to the body wall differentiate into […] and form […]

Answer 17

chrondrocytes
hyaline cartilage models

**provide template for bone formation

Question 18

[…] signaling helps to pattern the proximal segment

Answer 18

retinoic acid

Question 19

the AER expresses […] to maintain the undifferentiated cell zone

Answer 19

FGF4 and 8

Question 20

the […] zone moves distally over time as the limb lengthens

Answer 20

differentiation

Question 21

what helps to pattern segment identity of the limb?

Answer 21

Hox genes

Question 22

types and shapes of the bones in limbs are regulated by

Answer 22

HOX genes

Question 23

[…] and […] help pattern the segments in the proximal-distal axis

Answer 23

HOX genes and retinoic acid

Question 24

stylopod forms [2]

Answer 24

humerus, femur

**proximal

Question 25

zeugopod forms [4]

Answer 25

radius/ulna tibia/fibula

Question 26

autopod forms [4]

Answer 26

carpals/metacarpals tarsals/metatarsals **distal

Question 27

digit formation occurs via [...] in AER

Answer 27

programmed cell death

Question 28

shortened digits

Answer 28

brachydactyly

Question 29

fused soft tissue/bones of digits

Answer 29

syndactyly

Question 30

extra digits which lack proper muscle connections

Answer 30

polydactyly

Question 31

abnormal cleft between 2nd and 4th digits and 3rd digit absent. Other digits are fused

Answer 31

cleft hand/foot

Question 32

regulated by zone of polarizing activity

Answer 32

anterior-posterior axis

Question 33

ZPA produces [...] which leads to the expresion of [...]

Answer 33

retinoic acid SHH

Question 34

contributes to posterior specification of the posterior AP axis

Answer 34

SHH **pinky

Question 35

signaling molecule for dorsal axis

Answer 35

WNT-7

Question 36

signaling molecule for ventral axis

Answer 36

engrailed

Question 37

what axis determines future limb muscle compartments prior to limb rotation events?

Answer 37

ventral-dorsal

Question 38

prior to limb rotation, extensors are

Answer 38

dorsal

Question 39

prior to limb rotation, flexors are

Answer 39

ventral

Question 40

skeletal muscle development is regulated by [...] and [...] in the somite

Answer 40

MyoD and MYF5

Question 41

once the skeletal muscles are differentiated they express

Answer 41

dystrophin

Question 42

in the 7th week, the upper limbs rotate 90 degrees [...] and the lower limbs rotate 90 degrees [...]

Answer 42

upper: laterally lower: medially **why thumb is lateral and great toe is medial

Question 43

3 major processes in limb vascular system development

Answer 43

vasculogenesis angiogenesis vascular remodeling

Question 44

what artery supplies the upper limb bud

Answer 44

subclavian

Question 45

what artery supplies the lower limb bud

Answer 45

external iliac gives rise to femoral

Question 46

absence or partial loss of pectoralis major

Answer 46

poland sequence

Question 47

may result for disruption of blood flow to embryonic tissues of chest wall and hand affects subclavian artery formation

Answer 47

poland sequence

Question 48

complete absence of upper or lower limbs

Answer 48

amelia

Question 49

partial absence of limbs

Answer 49

meromelia

Question 50

long bones absent, but rudimentary hands/feet attached to trunk

Answer 50

phocomelia

Question 51

all limb segments present, but short

Answer 51

micromelia

Question 52

potential causes of limb defects [4]

Answer 52

proximal/distal axis disruption teratogens decreased/loss FGF signaling genetic (altered HOX)

Question 53

anti-angiogenic and may affect vasularization of the limb buds

Answer 53

thalidomide

Question 54

[...] limbs are more susceptible to thalidomide induced defects

Answer 54

upper **because they develop first

Question 55

scleraxis is the early marker for

Answer 55

tendons and ligaments

Question 56

cell death in the center of the mesenchyme creates future [...] space

Answer 56

joint cavity

Question 57

"curving of joints" that causes inability to perform active extension and flexion

Answer 57

arthrogryposis

Question 58

teeth present at birth

Answer 58

natal teeth

Question 59

lack of any dystrophin means

Answer 59

Duchenne's MD

Question 60

signaling molecules that establish the anterior/posterior axis

Answer 60

retinoic acid SHH

Question 61

regulates growth and development in the proximo-distal axis

Answer 61

apical ectodermal ridge

Question 62

signaling molecules that establish the proximo-distal axis

Answer 62

FGF 4 and 8

Question 63

signaling molecule that regulates development of the dorso-ventral axis

Answer 63

wnt-7a (dorsal) engrailed (ventral)

Question 64

tendon and ligament precursor

Answer 64

scleraxis

Question 65

the zone of polarizing activity is responsible for [2]

Answer 65

secretion of retinoic acid anterior-posterior limb patterning

Question 66

establishment of the apical ectodermal ridge is crucial to [...] patterning

Answer 66

proximal distal

Question 67

limb outgrowth is initiated by

Answer 67

FGF10 (proximal distal patterning)

Question 68

maintenance of the undifferentiated zone is sustained by

Answer 68

FGF4 and 8 (proximal distal patterning)

Question 69

results from retinoic acid induced SHH signaling emanating from the ZPA

Answer 69

anterior posterior axis

Question 70

[...] signaling leads to formation of the posterior elements

Answer 70

SHH

Question 71

engrailed secretion in the ventral ectoderm and Wnt7a signaling affect [...] patterning

Answer 71

dorsal-ventral

Question 72

give rise to axial cartilage and bone

Answer 72

sclerotomes

Question 73

gives rise to the connective tissue of the dermis of the back

Answer 73

dermatome

Question 74

gives rise to the muscles of the back and body wall

Answer 74

myotome

Question 75

ventrolateral migratory cells contribute to muscles of [2]

Answer 75

body wall and limbs