090914 dev spine rib sternum Flashcards
paraxial mesoderm
somatic mesoderm
form what kinds of skeletal structures
paraxial-vertebral column and ribs
somatic-sternum and limb skeleton
scleratome
the mesenchymal cells from medial and ventral part of somite; they are displaced medially to form bone
what influences scleratome?
signals from notochord and neural tube nearby
why does scleratome tissue organize into cranial and caudal divisions?
so resegmentation can occur so that skeletal muscle derived from dermomyotomes can cover adjacent vertebrae
central scleratome gives rise to
pedicle
proximal rib
ventral scleratome gives rise to
vertebral body
IV disc
dorsal scleratome gives rise to
dorsal part of neural arch
spine
lateral scleratome gives rise to
distal rib
somitocoel gives rise to
vertebral joints
IV disc
proximal ribs
cells from cranial half of scleratome give rise to
vertebral body
small part of neural arch
distal rib (thoracic region)
what is the costal process an ex of
regionalization of vertebrae
how does the cranial cadual axis influence the type of vertebrae formed?
because of Hox genes and retinoic acid expressed in a cranial to caudal axis
by week 8, what do you see in terms of vertebrae growth
3-4 primary ossification centers
when does the neurocentral jxn of vertebrae close?
3-6 yrs
when do secondary ossification centers form for vertebrae?
at puberty
