Skeletal Tissue: Development

Question 1

Bone formation occurs in these 2 ways

Answer 1

Intramembranous ossification (flat bone)
Endochondral ossification (weight bearing bones)

Question 2

Type of bone formation that occurs for flat bones

Answer 2

Intramembranous ossification

Question 3

Type of bone formation that occurs for weight-bearing bones like extremities and vertebrae-axial skeleton

Answer 3

Endochondral ossification

Question 4

Type of bone formation:
Ossification without cartilage formation

Answer 4

Intramembranous

Question 5

Type of bone formation:
Forms trabeculae resembling a sponge, also called spongy bone

Answer 5

Intramembranous

Question 6

During Intramembranous ossification, osteoblast secretion of this leads to mineralization and osteocyte development

Answer 6

Calcium phosphate

Question 7

Type of bone formation:
Bone matrix appears in histological sections as small, irregularly shaped spicules and trabeculae

Answer 7

Intramembranous

Question 8

What occupies the spaces in between immature bone during intramembranous ossification?

Answer 8

Connective tissue and blood vessels

Question 9

Type of bone formation that exists in pre-existing cartilaginous models

Answer 9

Endochondral ossification

Question 10

This is the first sign of Endochondral ossification

Answer 10

The appearance of a cuff of bone around the cartilage model

Question 11

The appearance of a cuff of bone around the cartilage model is the first sign of this type of bone formation

Answer 11

Endochondral ossification

Question 12

Chondrocytes are derived from this

Answer 12

Perichondrial cells

Question 13

Perichondrial cells give rise to this type of cell

Answer 13

Chondrocytes

Question 14

A transverse disc of cartilage that remains due to the formation of the primary and secondary ossifications during endochondral ossification

Answer 14

Epiphyseal growth plate

Question 15

This is the primary ossification center as a result of endochondral ossification

Answer 15

Diaphysis

Question 16

This is the secondary ossification center as a result of endochondral ossification

Answer 16

Epiphysis

Question 17

The cartilage of this is responsible for maintaining the growth process after endochondral ossification

Answer 17

Epiphyseal growth plate

Question 18

During indirect healing after a fracture, these differentiate into periosteal cells, fibroblasts, or chondroblasts (cartilage) forming a soft callus

Answer 18

Osteoprogenitor cells

Question 19

Type of bone healing where a blot clot of hematoma first forms at this site

Answer 19

Indirect healing

Question 20

Smooth muscle is derived from this

Answer 20

Visceral splanchnic mesoderm

Question 21

Mesodermal (mesenchymal) cells give rise to these long, spindle shaped cells that do not fuse and remain mononucleated

Answer 21

Myogenic cells / myoblasts

Question 22

Ciliary muscle and sphincter pupillae of the eye are smooth muscle derived from this

Answer 22

Neural crest cells

Question 23

Cardiac muscle is derived from this

Answer 23

Visceral splanchnic mesoderm that is found surrounding the heart tube

Question 24

Cardiac myoblasts are derived from this

Answer 24

Mesenchyme

Question 25

Skeletal muscle is derived from this

Answer 25

Paraxial mesoderm

Question 26

Post-mitotic myoblasts begin to synthesize these 2 things

Answer 26

Actin and myosin

Question 27

These form from myoblasts/myocytes and synthesize actin, myosin, troponin, tropomyosin and other muscle proteins

Answer 27

Myotubes / myofibers

Question 28

Primary myogenesis occurs during this stage of development

Answer 28

Embryonic stage (up to 8 weeks)

Question 29

Secondary myogenesis occurs during this stage of development

Answer 29

Fetal stage (8 weeks to birth)

Question 30

At what week in development do mesenchymal cells of myotomes, as well as of specialized condensed (premuscle) areas of mesenchyme modulate into myoblasts, which begin to aggregate into syncytial tubes

Answer 30

4 weeks

Question 31

At what week in development have syncytial myotubes formed primitive muscle fibers in which longitudinal myofilaments appear Myotubes grow in length by incorporating additional myoblasts

Answer 31

5 weeks

Question 32

At what week in development have more myofilaments appeared, but nuclei are still centralized Growth in length continues through addition of myoblasts

Answer 32

9 weeks

Question 33

Myotubes grow in length through addition of these

Answer 33

Myoblasts

Question 34

These grow in length by addition of myoblasts

Answer 34

Myotubes

Question 35

At what month in development have muscle fibers become thicker as myofilaments have multiplied and differentiated into thin (actin) and thick (myosin) myofilaments arranged in alternate overlapping bands, giving a cross-striated appearance Nuclei move peripherally Growth in length continues through addition of myoblasts

Answer 35

5 months

Question 36

Are nuclei centralized or have they moved peripherally at 9 weeks development?

Answer 36

Still centralized

Question 37

Are nuclei centralized or have they moved peripherally at 5 months of development?

Answer 37

Move peripherally

Question 38

This arrests muscle growth when a muscle has attained its normal size

Answer 38

Myostatin

Question 39

In the absence of this function, animals develop a grossly hypertrophic musculature

Answer 39

Myostatin

Question 40

Myostatin arrests this

Answer 40

Muscle growth (when a muscle has attained its normal size)

Question 41

In the trunk region, each myotome partitions into these

Answer 41

A doral epimere and ventral hypomere

Question 42

Partition of trunk myotome that develops into the extensor muscles of the neck and vertebral column

Answer 42

Epimere (epaxial)

Question 43

Partition of trunk myotome that develops into the scalene, prevertebral, geniohyoid, infrahyoid, intercostal, abdominal muscles, lateral and ventral flexors of the vertebral column, quadratus lumborum, and pelvic diaphragm

Answer 43

Hypomere (hypaxial)

Question 44

Myoblasts proliferate and exit the cell cycle to terminally differentiate to form this

Answer 44

Myocytes

Question 45

These cells express contractile proteins such as actin and myosin and fuse to form myofibers, each of which consists of a multinucleated syncytium (i.e. a cellular mass with multiple nuclei) containing contractile myofibrils

Answer 45

Myocytes

Question 46

Upper limb forms at this many days gestations

Answer 46

26

Question 47

Lower limb forms at this many days gestations

Answer 47

28

Question 48

Upper or lower limb: Forms opposite of caudal cervical segments

Answer 48

Upper

Question 49

Upper or lower limb: Forms an apical ectodermal ridge (AER)

Answer 49

both

Question 50

Upper or lower limb: Rotates 90 degrees laterally

Answer 50

Upper

Question 51

Upper or lower limb: Forms opposite of the lumbar and upper sacral segments

Answer 51

Lower

Question 52

Upper or lower limb: Rotates 90 degrees medially

Answer 52

Lower

Question 53

Major muscle mass that develops into the extensor and supinator musculature of the upper limb and the extensor and abductor musculature of the lower limb

Answer 53

Posterior condensation

Question 54

Major muscle mass that develops into the flexor and pronator musculature of the upper limb and the flexor and adductor musculature of the lower limb

Answer 54

Anterior condensation

Question 55

Each limb bud consists of a ______ core covered by a layer of ectoderm

Answer 55

Mesenchymal

Question 56

Each limb bud consists of a mesenchymal core covered by a layer of this

Answer 56

ectoderm

Question 57

This migrates into the limb bud to give rise to vasculature and skeletal formations

Answer 57

Lateral plate mesoderm

Question 58

Limb buds elongate by proliferation of this

Answer 58

Mesenchyme

Question 59

Chondrification centers form during this week of development

Answer 59

5th

Question 60

Cartilaginous limbs form during this week of development

Answer 60

6th

Question 61

Osteogenesis occurs in the limbs during this week of development

Answer 61

7th

Question 62

Primary ossification centers form in limbs during this week of development

Answer 62

12th

Question 63

This induces development of primordial phalanges

Answer 63

Apical epidermal ridge (AER)

Question 64

Webbing of the fingers or toes

Answer 64

Syndactyly

Question 65

Hand/foot plates form digital rays during this week of development

Answer 65

6/7th week

Question 66

Digital rays form separate digits at this week of development

Answer 66

8th

Question 67

Area of skin supplied by a single spinal nerve

Answer 67

Dermatome

Question 68

Drug that was used to alleviate morning sickness in pregnant women Has been linked to Phocomelia/Focomelia (reduced/missing arms and/or legs)

Answer 68

Thalidomide

Question 69

Hyperextension and incurving of the feet Occurs from abnormal positioning or restricted movement of the lower limbs of the fetus in utero (genetic and environmental factors together) All anatomical structures are present French (taping) method or Ponseti (casting) method No discomfort or pain

Answer 69

Talipes Equinovarus

Question 70

What is Talipes Equinovarus?

Answer 70

Hyperextension and incurving of the feet (clubfoot) Occurs from abnormal positioning or restricted movement of the lower limbs of the fetus in utero (genetic and environmental factors together)