Bone Embryology Flashcards
Gestational age for formation of appendicular system?
4weeks
Notochord expresses which protein?
Shh protein
What regulates limb bud formation? (2)
HOX
SHH protein
Limb bud is combination of which two mesoderm?
Somatic and lateral plate
Limb bud has mesenchymal core with a thick ectodermal cap called?
Active ectodermal ridge
AER formas under which FGF?
10
Defect in AER results in which defect?
Limb truncation
Most important FGF in AER and longitudinal growth of limb?
FGF8
First signalling centre?
AER
Second signalling centre?
ZPA
ZPA controlled by which gene?
SHH
High conc of Shh on which side of ZPA?
Small finger development
Abnormally high SHH on ulnar aspect creates which abnormality?
Polydactyly
Abnormally high SHH on radial side results in which abnormality?
Loss of thumb
Third signalling centre?
Non-AER limb ectoderm/
Progress zone
Progress zone controlled by which gene?
Wnt7a
Antagonist to WNT7a?
engrailed-1 protein
WNT7a responsible for which features?
Dorsal features incl fingernails
HOX genes responsible for?
Patterning digit formation
Duplication of ZPA would create which abnormality?
Mirror image limb duplication
Spinal column originates from pairs of mesodermal structures called?
Somites
Somites have 3 layers:
- Sclerotome
- Myotome
- Dermatome
Dorso-ventral patterning of neural tube determined by?
- Shh
2. Canonical Went/B catenin
Neural crest forms which structures (4)
PNS, pia mata, spinal ganglia and sympathetic trunk
In vertebrae notochord forms? (2)
Ant vertebral bodies
Nucleus Pulposus
Annulus fibrosis is formed from?
Sclerotome
Transcription factors involved in chondrocyte regulation?
SOX 9
PTHrP
Compression across the GP slows what type of growth? Who’s law?
Longitudinal growth
Heuter-Volkmann Law
Zones of growth plate? (6)
- Resting zone
- Proliferation
- Hypertrophy
- Spongiosa
- Groove of ranvier
- La Croix ( Perichondrial fibrous ring)
Roly Poly Help Skeletons Grow Long
Physeal hypertrophic zone phases (3)?
- Maturation
- Degeneration
- Provisional calcification
Zone involved in physeal injuries?
Provisional calcification
NB substance produced by chondrocytes involved in mineralization?
Type X Collagen
Two type of spongiosa?
Primary and secondary
Physeal zone with highest rate of extracellular matrix production>
Prolif zone
What happens at spongiosa? (3)
Vascular invasion
OB align on cartilage bars
Mineralized to form woven bone then remodelled to form secondary spongiosa
Chondrocyte maturation regulated by? (2)
Indian HH protein
PTHrP
Responsible for appositional bone growth?
Groove of ranvier
Anchors and supports the physis?
Fibrous ring of La Croix
Steps of embryonic long bone formation? (5)
- Vascularization
- 1 ossification centres form
- cartilage model
- marrow forms
- 2 ossification centres
Embryonic flat bone formation through which ossification?
Intramembranous
2 major differences between intramembranous and endochondral healing?
Intramem =
- No resorption at bone ends
- No cartilage model
What happens to 02 tension as you go deeper through the layers of physis?
Decreases
What inhibits BMP to form joints of the body?
Noggin