Musculoskeletal Development I Flashcards
Skeletal tissue is ______ in origin
Mesenchymal
What structures do the Mesodermal scletotomes (of somites) give rise to?
Vertebral column
Ribs
Sternum
What structures do the Lateral plate mesoderm give rise to?
Limb bones
Girdles
What structures do the head of the mesoderm give rise to?
Calvaria and base of the skull
During the Bone/Cartilage differentiation pathway, what promotes mesenchymal cells to undergo condensation (grouping together/clumping)?
N-Cadherins
During the Bone/Cartilage differentiation pathway, ______ stimulates the synthesis of fibronectin and N-CAM
TGF-Beta
During the Bone/Cartilage differentiation pathway, the membranous pathway requires what transcription factors?
If they go through this pathway, what do mesenchymal cell become?
Runx-2
Osx
Osteoblasts
During the Bone/Cartilage differentiation pathway, for the permanent cartilage pathway what does mesenchymal condensation form?
Chondroblasts
During the Bone/Cartilage differentiation pathway, for th epermanent cartilage pathway what are the affects of Sox9?
Causes chondroblasts to secrete collagen II and cartilage matrix
Is continuously expressed in permanent cartilage
During the Bone/Cartilage differentiation pathway, for the endochondral bone pathway what 3 factors induce the cartilage to undergo hypertrophy?
Runx-2
Indian Hedgehog (Ihh)
BMP-6
During the Bone/Cartilage differentiation pathway, for the endochondral bone pathway what do hypertrophic cartilage cells secrete?
VEGF- Vascular endothelial growth factor
What are the effects of VEGF?
Invading blood vessels erode the hypertrophic acrtilage and bring osteoblasts to replace cartilage with bone
What parts of the vertebra are the centrum derived from?
Ventral and medial parts of paired sclerotomes
What parts of the vertebra are the neural arches derived from?
Dorsal regions of the sclerotome
What does proximal development of costal processes/ribs depend on?
Myotomic myogenic factors Myf-5 and Myf-6
What does distal development of costal processes/ribs depend on?
BMP signals from somatopleural mesoderm
Describe the Atlas bone
It is the first cervical vertebral bone
Your world is in your head and this bone holds your head up, hence the greek mythological man Atlas holding up the world
Allows for the yes movement
Describe the Axis bone
It is the second cervical vertebral bone
Allows for you to turn you head in the no direction
Describe the development of the sternum in terms of where it is derived from
Derived from the lateral plate mesoderm
Where do clavicles arise from?
Neural crest
What pathway do clavicles develop from?
Intramembranous pathway
What is the one of the first bones to become ossified?
Clavicles
What are the 3 major components of the embryonic skull components?
- Neurocranium
- Viscerocranium
- Occipital Sclerotomes
Describe the Neurocranium of the embryonic skull
Part of the skull that surrounds the brain
What are the 2 portions of the Neurocranium
- Cartilaginous portion- Forms the base of the skull
- Membranous portion
What does the cartilaginous Neurocranium give rise to?
-Occipital, phenoid, ethmoid, and parts of the temporal
What does the membranous Neurocranium give rise to?
-Part of the occipital, parietals, frontals, and parts of the temporal
What does the Viscerocranium surround?
- The oral cavity and pharynx
- Viscerocranium refers to the pharyngeal arches
Elongation of primary ossification centers is due to _____
Shh
What are Neurocranium bones characterized by?
A transient appearance of type II collagen and cartilage specific proteoglycan
What causes the closure of sutures (portion between bones in the skull)
The inhibition of Noggin on BMP
Differentiate the Hox gene boundaries for the different regions of the vertebral column.
Occipital-Cervical Boundary- Hox3
Cervical-thoracic Boundary- Hox6
Attached Floating Ribs- Hox9
What is the relationship of Hox gene expression and the development of the vertebral column?
Amount of Hox Expression
Occipital < Caudal < Sacral < Lumbar < Cervical < Thoracic
How does retinoic acid affect the expression of the Hox genes and the development of the vertebral column?
Retinoic Acid regulates Hox gene expression by binding to its enhancer sequence to increase expression of Hox
What are homeotic transformations?
The transformation of one organ into another, arising from a mutation in homeotic genes.
What is the primordium for the atlas?
Cervical Somites 1 and 2 –> C1 Vertebra –> Atlas
What is the primordium for the axis?
Cervical Somites 2 and 3 –> C2 Vertebra –> Axis
What do pharyngeal arches compose?
They are the cartilaginous portions of the viscerocranium
