Term
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Definition
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Definition
| also "Hox genes"; regulate limb patterning in vertebrates |
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| AER; multilayered epithelial structure at tip of developing limb that helps induce mesenchymal growth via endogenous fibroblast growth factors (FGFs), etc. |
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| zone of polarizing activity |
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Definition
| ZPA; posterior aggregation of mesenchymal cells- instructs posteior/anterior limb bud development |
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Definition
| programmed cell death; in this instance, allows degradation of interdigital tissue breakdown to separate digits |
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Definition
| webbing or fusion of the digits |
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Definition
| mesenchymal bone models--> cartilaginous skeleton |
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Definition
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| primary ossification centers |
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Definition
| beginning 7th week, provide cartilage-->bone transformation |
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Definition
| appear at beginning of fetal period; coincides with functional differentiation of muscles |
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Term
| blood supply to limb buds |
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Definition
dorsal intersegmental arteries--> primary axial artery; branches during development, ultimately:
brachial artery in upper arm
ant. interosseous artery in forearm
deep artery of thighant.post tibial arteries in leg |
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Term
| most critical period for limb development? |
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Definition
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Definition
| shortness of digits due to shortened phalanges |
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Definition
| supernumerary digits, often extra digit is incompletely formed |
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Definition
| webbing of digits; more frequent in foot; results from failure of webs to degenerate |
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Definition
| failure of notches of digital rays to develop (~7 weeks); results in fusion of bones between digits |
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Term
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Definition
| absence of limb due to anomalous development of limb buds during ~4 weeks |
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Term
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Definition
| arrest/disturbance of differentiation/growth in limbs during ~5 weeks- partial limbs present |
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Term
| sequence of limb bud development |
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Definition
upper- visible day 26 or 27
lower- usu. appear 2 days after upper |
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