skeletal system development Flashcards
what does paraxial mesoderm form?
somites (occipital)
somitomeres (head)
what embryological layers make the skeletal system?
paraxial mesoderm
lateral plate mesoderm
neural crest cells
what does lateral plate mesoderm form?
pelvic and shoulder girdles
bones of the limbs
what do the neural crest cells form?
in the head, the bones of the face and skull
what specifically forms the neurocranium (protective part around the brain)?
neural crest cells and paraxial mesoderm
the bones of the chondrocranium in front of the rostral limit of the notochord are derived from what?
neural crest cells
bones of the chondrocranium in back of the rostal limit of the notochord are derived from what?
occipital sclerotomes (paraxial mesoderm)
viscerocranium forms what?
bones of the face
the 1st arch dorsal portion (maxillary process) gives rise to what?
maxilla, zygomatic bone, temporal bone
1st arch ventral portion (mandibular process) gives rise to what?
meckel cartilage, malleus, incus, and stapes
what are sutures derived from?
neural crest and paraxial mesoderm
what are limb buds derived from?
core of lateral plate mesoderm covered by ectoderm
what is the apical ectodermal ridge?
a band of mesoderm that develops at the distal end of limb bud to keep the distal mesoderm from differentiating
how do fingers and toes form?
by cell death in the AER that separates it into 5 parts then segments continue to grow
what happens in terms of rotation around 7 weeks?
the limbs rotate in opposite directions (lower medially and upper laterally)
what factors insure that digits appear in the correct order?
ZPA produces retinoic acid which induces SHH
which growth factors are needed for proximodistal patterning (AER maintaining )?
FGF-10 initiates outgrowth
BMF’s induce AER and radical fringe + engrailed keep it there
FGF-4 + FGF-8 maintain everything
how do we get things to be dorsal and ventral?
Dorsal: WNT7a induces LMX1= dorsal cells
Ventral: BMPs found in ventral cells which represses WNT7a
the notochord becomes what adult structure?
the nucleus pulposus
what does the the sternum develop from?
somatic mesoderm in the ventral body wall
