Bone Embryology

Question 1

Gestational age for formation of appendicular system?

Answer 1

4weeks

Question 2

Notochord expresses which protein?

Answer 2

Shh protein

Question 3

What regulates limb bud formation? (2)

Answer 3

HOX

SHH protein

Question 4

Limb bud is combination of which two mesoderm?

Answer 4

Somatic and lateral plate

Question 5

Limb bud has mesenchymal core with a thick ectodermal cap called?

Answer 5

Active ectodermal ridge

Question 6

AER formas under which FGF?

Answer 6

10

Question 7

Defect in AER results in which defect?

Answer 7

Limb truncation

Question 8

Most important FGF in AER and longitudinal growth of limb?

Answer 8

FGF8

Question 9

First signalling centre?

Answer 9

AER

Question 10

Second signalling centre?

Answer 10

ZPA

Question 11

ZPA controlled by which gene?

Answer 11

SHH

Question 12

High conc of Shh on which side of ZPA?

Answer 12

Small finger development

Question 13

Abnormally high SHH on ulnar aspect creates which abnormality?

Answer 13

Polydactyly

Question 14

Abnormally high SHH on radial side results in which abnormality?

Answer 14

Loss of thumb

Question 15

Third signalling centre?

Answer 15

Non-AER limb ectoderm/

Progress zone

Question 16

Progress zone controlled by which gene?

Answer 16

Wnt7a

Question 17

Antagonist to WNT7a?

Answer 17

engrailed-1 protein

Question 18

WNT7a responsible for which features?

Answer 18

Dorsal features incl fingernails

Question 19

HOX genes responsible for?

Answer 19

Patterning digit formation

Question 20

Duplication of ZPA would create which abnormality?

Answer 20

Mirror image limb duplication

Question 21

Spinal column originates from pairs of mesodermal structures called?

Answer 21

Somites

Question 22

Somites have 3 layers:

Answer 22

1. Sclerotome
2. Myotome
3. Dermatome

Question 23

Dorso-ventral patterning of neural tube determined by?

Answer 23

1. Shh

2. Canonical Went/B catenin

Question 24

Neural crest forms which structures (4)

Answer 24

PNS, pia mata, spinal ganglia and sympathetic trunk

Question 25

In vertebrae notochord forms? (2)

Answer 25

Ant vertebral bodies | Nucleus Pulposus

Question 26

Annulus fibrosis is formed from?

Answer 26

Sclerotome

Question 27

Transcription factors involved in chondrocyte regulation?

Answer 27

SOX 9 | PTHrP

Question 28

Compression across the GP slows what type of growth? Who's law?

Answer 28

Longitudinal growth | Heuter-Volkmann Law

Question 29

Zones of growth plate? (6)

Answer 29

1. Resting zone 2. Proliferation 3. Hypertrophy 4. Spongiosa 5. Groove of ranvier 6. La Croix ( Perichondrial fibrous ring) Roly Poly Help Skeletons Grow Long

Question 30

Physeal hypertrophic zone phases (3)?

Answer 30

1. Maturation 2. Degeneration 3. Provisional calcification

Question 31

Zone involved in physeal injuries?

Answer 31

Provisional calcification

Question 32

NB substance produced by chondrocytes involved in mineralization?

Answer 32

Type X Collagen

Question 33

Two type of spongiosa?

Answer 33

Primary and secondary

Question 34

Physeal zone with highest rate of extracellular matrix production>

Answer 34

Prolif zone

Question 35

What happens at spongiosa? (3)

Answer 35

Vascular invasion OB align on cartilage bars Mineralized to form woven bone then remodelled to form secondary spongiosa

Question 36

Chondrocyte maturation regulated by? (2)

Answer 36

Indian HH protein | PTHrP

Question 37

Responsible for appositional bone growth?

Answer 37

Groove of ranvier

Question 38

Anchors and supports the physis?

Answer 38

Fibrous ring of La Croix

Question 39

Steps of embryonic long bone formation? (5)

Answer 39

1. Vascularization 2. 1 ossification centres form 3. cartilage model 4. marrow forms 5. 2 ossification centres

Question 40

Embryonic flat bone formation through which ossification?

Answer 40

Intramembranous

Question 41

2 major differences between intramembranous and endochondral healing?

Answer 41

Intramem = 1. No resorption at bone ends 2. No cartilage model

Question 42

What happens to 02 tension as you go deeper through the layers of physis?

Answer 42

Decreases

Question 43

What inhibits BMP to form joints of the body?

Answer 43

Noggin