Glossary of Skeletal Development Hankin Block II Unit I
Other Decks By This User
- What sort of ossification forms the clavicle?
- What does the paraxial mesoderm form?
- Future somites.
- What are the two layers of lateral plate mesoderm?
- Parietal and visceral layers.
- When does skeletal development begin in the embryonic period?
- Week 4.
- What are cartilage and bone of the body derived from?
- What does the sclerotome form?
- Axial skeleton in body and some in head.
- What does lateral plate mesoderm form?
- Appendicular skeleton and body wall (soma)
- What forms the vertebral column?
- Sclerotome (mesenchyme)
- What induces sclerotome formation? What secretes these proteins?
- Noggin and Sonic hedgehog induce sclerotome formation and are secreted by the notochord and neural tube floor plate.
- What does PAX 1 do? What expresses it?
- PAX1 initiates a cascatde of cartilage and bone forming genes for vertebral column development. It is expressed by Scleretome cells.
- How are the vertebrae formed?
- Endochondral ossification of sclerotome regions.
- How do the ribs develop?
- As outgrowths of lateral processes of thoracic vertebrae.
- How is the sternum formed?
- First seven ribs unite ventrally to form sternum.
- How many somite pairs are there? Occipital, Cervical, Thoracic, Lumbar, Sacral, coccygeal?
- What forms the base of the skull?
- The first cervical and occiptal somites.
- How are vertebrae formed?
- By fusion of sclerotome cells from two somite levels.
- When do sclerotome cells surround the developing neural tube and notochord?
- During week 4.
- What part of each vertebrae forms a centrum (future body) around the notochord?
- The ventral part.
- What does the dorsal part of each vertebrae form?
- Costal prcesses (transverse), vertebral arch.
- WHat forms the nucleus pulposis?
- What do spinal nerves pass through?
- Intervertebral foramen.
- What do cells from the proatlas contribute to?
- Formation of basiocciptal bone and dens.
- What does the normal atlas form?
- The anterior arch instead of body.
- What stimulates cells to express PAX1?
- SHH (sonic hedgehog)
- What guides ventromedial sclerotome cells to form centrum?
- What does induction of the roof plate of neural tube result in?
- PAX9, MSX1, and MSX2 expression.
- What do PAX9, MSX1, and MSX2 do?
- Guide lateral sclerotome to form dorsal vertebral arch.
- How are individual vertebrae specified?
- Specific combinations of Hox genes.
- What is Klippel Feil syndrome?
- Short neck/decreased cerical motion, multiple fused cervical somites.
- What causes Hox gene misexpression?
- Retinoic acid.
- What activates cranial caudal gradient of hox genes?
- Retinoic acid.
- What causes spinal bifida (2)?
- 1) Failure of normal vertebral induction.
2) Failure of the neural tube to close dorsally.
- What do ribs develop from? How?
- Costal processes of thoracic vertebrae. Sclerotome cells migrate within somatic lateral plate mesoderm around the body curvature toward the ventral surface.
- Which ribs form the sterum?
- First 7
- What does the sternum arise from?
- A pair of cartilagenous bands around the ventral midline.
- What is cleidocranial dysplasia?
- Abnormal development of head. Flat wide nose, no bridge, supernumerary and unerupted teeth, aplasia of clavicles.
- What is included in the appendicular skeleton?
- Appendicular girdles, intrinsic limbbones.
- What type of ossification forms the appendicular skeleton?
- Endochondral ossification.
- What does somatic lateral plate mesoderm form?
- All cartilages and bones of appendicular skeleton, and the body wall.
- What does the somitic sclerotome form?
- All cartilages and bones of axial skeleton in the body (some in head).
- When are limb buds visible?
- End of week 4.
- What is the mesenchyme core of limbs formed by?
- Derivied from somatic layer of lateral plate mesoderm.
- What surrounds the mesenchyme core of the limbs?
- What are the 3 things found initially in the limb bud? What do each of them form?
- Mesenchyme from lateral plate mesoderm (forms skeleton, CT, and some blood vessels)
Mesenchymal from somites (forms muscle)
Neural crest cells (forms schwann cells and melanocytes)
- What is the apical ectodermal ridge? What does it do?
- A thickend distal border of the limb bud that exerts an inductive influence on the underlying mesenchyme. IT prevents its differnetiation and causes it to proliferate rapidly.
- What does the dorsal ectoderm of the limb bud do?
- Expreses radical fringe (signalling molecule)
- What does the ventral ectoderm do?
- Expresse engrailed (transcription factor)
- WHat is limb outgrowth initiated by?
- Factors secreted by lateral plate mesoderm.
- WHat induces apical ectodermal ridge formation?
- Bone modeling proteins (homeobox gene MSX2)
- What restricts the apical ectodermal ridge to the distal tip of thel imb?
- The radical fringe (dorsal ectoderm)
- What does the radical fringe induce?
- What produces engrailed? What does it do?
- Ventral ectoderm represses expression of the radical fringe to maintain the border.
- What do FGF4 and FGF8 do?
- Maintain a progress zone in the developming limp of rapidly proliferating mesenchymal cells adjacent to apical ectodermal ridge.
- What happens to proximal mesenchymal cells as they move further from the AER?
- Decrease rate of division and begin differentiation.
- What is the zone of polarizing activity?
- A cluster of cells at the posterior border of the limb (near flank)
- What determines the location of the zone of polarizing activity?
- Transcription factors.
- What do zone of polarizing cells produce?
- Retinoic acid which initiates expression of sonic hedgehog.
- What happens in the absence of sonic hedgehog?
- Regression of Apical ectodermal ridge.
- What determines proper location of the digits?
- Zone of polarizing activity.
- What is the patterning along the dorsoventral axis regulated by?
- Bone modeling proteins in ventral ectoderm.
- What does EN1 do?
- represses WNT7a expression and restricting it to dorsal ectoderm.
- What does WNT7a do?
- it induces LMX1 in dorsal mesenchyme and maintains sonic hedgehog expression in the zone of polarizing activity (indirectly affects anterior/posterior patterning)
- What does LMX1 do?
- Specifies cells to be dorsal.
- What patterns limbs along the proximodistal limb?
- Hoxd genes.
- What do mutations in Hoxd-13 cause?
- Reduction defects of digits.
- What does apoptosis play a role in?
- Formation of axillary region, radius/ulna, tibia/fibula.
- What do specific HOX expression results from?
- Combinatorial expression of SHH, FGFs and WNT7a.
- What determines digit identity?
- BMP concentration.
- What digit has the highest/lowest BMP concentration?
- Thumb = lowest
Pinky = highest
- Which direction do the legs rotate? The arms?
- Upper limbs rotate laterally. Lower limb rotates medially.
- What arrests limb divelopment?
- Removal of apical ectodermal ridge.
- What is amelia?
- Complete absence of limbs.
- What is phocomelia?
- Proximal structures absent, hands or feet attached to trunk by irregularly shaped bones.
- WHen does endochondral ossifaction begin?
- End of embryonic period (week 12)
- What forms the joint cavity?
- Surrounding cells, cartilagenous condensations, and cell death. (WNT14 appears to be the inductive signal)
You must Login or Register to add cards