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34 Cards in this Set

  • Front
  • Back
musculo system from?
ectoderm, mesoderm, neural crest
inducing center?
pharyngeal arches
involved in structures of the face
"head somites"; less well-developed and in head region
ectodermally covered and mesodermally cored; arranged in segmental distribution
limb buds
one for upper and one for lower extremity
paraxial mesoderm
assoc with somites and somitomeres, forming vertebra, ribs, and all striated skeletal muscle
lateral plate mesoderm
body wall structures
neural crest cells
bones and connective tissues of skull
ends up as nucleus pulposis of intervertebral discs
skull development: membranous neurocranium
membranous neurocranium; membranous ossification, most derived from neural crest cells; back portion of skull from somitomeres and jaw and maxilla are neural crest; exception: inferior part of occipital and otic capsule derived from paraxial mesoderm somitomeres
skull deformities assoc with premature closure of sutures
scaphocephaly wedge skull: premature sagittal closure
acrocephaly (tower skull): premature closure of coronal suture
somites in musculo development
1. sclerotome fuse and form vertebra
2. myotome cells migrate to lateral plate, limb buds, and pharyngeal arches to form muscle cells--epimere forms dorsal portion of myotome and intrinsic muscles of spine; hypomere forms ventral portion
3. dermatome cells from dermis of skin
spinal cord development
each vertebra formed from two somites
spinal bifida
vertebral arch fails to form
1. occulta: involves only bone, spinal cord intact.
2. cystica: protrusion of meninges and possibly spinal cor out over skin; more common in baby girls; most severe form involves failure of neural tube to fuse
cranial meningocoele
protrusions of the contents of cranial bulb out onto skin- occipital and frontal
limb development- external
starts at 4th week; AER induces rapid prolif of underlying mesenchyme; apoptosis in AER leads to 5 zones and fomration of fingers; ZPA induces patterning by releasing sonic hedgehog; digital rays-->notches--webbed fingers--separate fingers
internal events
1. myoblasts migrate and differentiate
2. motor neurons establish connections
3. sensory axons follow
4. neural crest cells form Schwann cells
5. mesenchyme farthest from AER forms cartilaginous model of bones
process proceeds from proximal to distal
POU gene family
homologous to segmentation genes in flies; Pit and Oct (materally derived Oct3 maintains the undiffernetiated state up to morula stage)
1,9: sclerotome prevertebral mesenchyme
3,7: dermamyotome, neural crest, muscle
HOX gene family
homo to fly homeobox genes;
mammalian maternal effect genes which have recently been described in mice and humans to initate activation of embryonic genome
homeobox genes
discovered in fruit flies; specify differences between body segments from head to rear; genes on chromosome in same order as activation on body axis; code for DNA binding proteins
HoxD genes 8-13
limb development
sets craniocaudal axis
sets proximal to distal axis
sets the anterior to posterior axis
establish a chemical gradient that provides positional info to migrating cells
cell adhesion molecules
cadherins (cell to cell)
integrin (transmembrane- cell to ECM)
txn factors
remain in cell of origin, bind to promotor or enhancer region; ex) zinc fingers
signaling molecules
produced by one cell and affect another cell; ex? growth factors and hedgehog proteins
receptor molecules
interact with signalers and gernerate 2nd messengers to alter DNA txn
causes of malfomration
genetic factors, environmental factors, mechanical factors
congenital anomalies
anencephaly, meningocoele, spina bifida, achondroplasia, cleft hand or foot, congenital absence of radius, brachydactyly, poly, syn, clubfoot, congenital dislocation of hips, Hox13 mutation (thumb and large toe displaced proximally, phalanges shortened, nails underdeveloped), amniotic banding, drugs