Lecture 18: Skeletal System Development I Flashcards
T/F: Skeletal tissue is mesodermal.
False, mesenchymal, not necessarily mesodermal
What do mesodermal sclerotomes form?
Vertebral column, ribs, sternum
What do lateral plate mesoderm form?
Limbs and girdles
What do head mesoderm form?
Calvaria and base of skull
What do neural crest form?
Facial bones
What occurs in the common pathway of bone/cartilage differentiation?
N-cadherins promote mesenchymal cell condensation & TGF-beta stimulates synthesis of fibronectin and N-CAM
What occurs in the membranous bone pathway of bone/cartilage differentiation?
Mesenchymal cells differentiate into osteoblasts via Runx-2 and Osx.
What occurs during the permanent cartilage pathway of bone/cartilage differentiation?
Mesenchymal condensation forms chondroblasts which secrete collagen II and cartilage matrix via Sox-9
What occurs during the endochondral bone pathway of bone/cartilage differentiation?
Runx-2, ihh, & BMP-6 induce cartilage to undergo hypertrophy and secrete bone proteins.
Blood vessels bring in osteoblasts to replace cartilage in bone
What is the centrum of a vertebra derived from?
Vental and medial paired sclerotomes
What do neural arches arise from?
Dorsal regions of sclerotomes
What does the proximal development of costal processes/ribs depend on?
Myf-5 and Myf-6
What does the distal development of costal processes/ribs depend on?
BMP from somatopleural mesoderm
Which Hox gene is associated with the occipital-cervical boundary?
Hox3
Which Hox gene is associated with the cervical-thoracic boundary?
Hox6
Which Hox gene is associated with the attached-floating rib boundary?
Hox9
Which Hox gene is associated with the thoracic-lumbar boundary?
Hox10
Which Hox gene is associated with the lumbar-sacral boundary?
Hox11
Which Hox gene is associated with the sacral-coccygeal boundary?
Hox13
Which Hox gene splits the proatlas anlage?
Hoxa-7
What happens when all Hox10 is knocked out?
Ribs form on all lumbar and sacral vertebrae
What is the primordium of the atlas?
Posterior C1 & anterior C2
What is the primordium of the axis?
Posterior C2 & anterior C3
What is the sternum derived from?
Lateral plate mesoderm
What does the clavicle arise from?
Neural crest
T/F: The clavicle is one of the first bones to be ossified.
True
Hypoplasia of the clavicle, delayed ossification of membrane bones, open anterior and posterior fontanelles in the skull, & supernumerary teeth are symptoms of what?
Cleidocranial dysplasia
